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Abstract:

A vehicle running control system includes: a speed pattern creating unit
that creates a speed pattern according to a target traveling path, a
running control unit that controls running of the vehicle based on the
speed pattern, a first speed condition correcting unit that correct speed
conditions in a direction from a start position of the running control
toward an end position of the running control on the target traveling
path, and a second speed condition correcting unit that correct speed
conditions in a direction from the end position of the running control
toward the start position of the running control on the target traveling
path.

Claims:

1. A vehicle running control system comprising:a speed pattern creating
unit that creates a speed pattern according to a target traveling path;a
running control unit that controls running of the vehicle based on the
speed pattern;a first speed condition correcting unit that corrects speed
conditions in a direction from a start position of the running control
toward an end position of the running control on the target traveling
path; anda second speed condition correcting unit that corrects the speed
conditions in a direction from the end position of the running control
toward the start position of the running control on the target traveling
path.

2. The vehicle running control system according to claim 1, wherein the
first speed condition correcting unit corrects acceleration-side speed
conditions, and the second speed condition correcting unit corrects
deceleration-side speed conditions.

3. The vehicle running control system according to claim 1, wherein the
first speed condition correcting unit and the second speed condition
correcting unit correct the speed conditions to lower speeds.

4. The vehicle running control system according to claim 3, further
comprising a traveling path dividing unit that divides the target
traveling path into a plurality of regions at fixed intervals,wherein the
first speed condition correcting unit and the second speed condition
correcting unit correct the speed condition for each of the regions into
which the target traveling path is divided, andwherein the first speed
condition correcting unit and the second speed correcting unit compare
the speed conditions of adjacent ones of the regions, and correct the
speed condition of one of the regions having the higher speed, to a lower
speed.

5. The vehicle running control system according to claim 3, further
comprising a traveling path dividing unit that divides the target
traveling path into a plurality of regions at fixed intervals,wherein the
first speed condition correcting unit and the second speed condition
correcting unit correct the speed condition for each of the regions into
which the target traveling path is divided; andthe first speed condition
correcting unit and the second speed condition correcting unit compare
the speeds of adjacent ones of the regions to determine an acceleration
or a deceleration across the adjacent regions, and corrects the
acceleration or the deceleration does not exceed an upper limit thereof.

6. The vehicle running control system according to claim 5, wherein the
first speed condition correcting unit and the second speed condition
correcting unit correct the acceleration or deceleration across the
adjacent regions by correcting the speed of one of the regions to a lower
speed.

7. The vehicle running control system according to claim 4, wherein:the
first speed condition correcting unit and the second speed condition
correcting unit calculate an addition vector of an acceleration or
deceleration across adjacent ones of the regions and a lateral
acceleration; andthe first speed condition correcting unit and the second
speed condition correcting unit correct a speed, based on the addition
vector and a friction circle of each of the regions.

8. The vehicle running control system according to claim 5, wherein:the
first speed condition correcting unit and the second speed condition
correcting unit calculate an addition vector of an acceleration or
deceleration across adjacent ones of the regions and a lateral
acceleration; andthe first speed condition correcting unit and the second
speed condition correcting unit corrects a speed, based on the addition
vector and a friction circle of each of the regions.

9. The vehicle running control system according to claim 7, wherein the
first speed condition correcting unit and the second speed condition
correcting unit correct the speed of one of the adjacent regions to a
lower speed, so that the addition vector does not go beyond the friction
circle of each of the regions.

10. The vehicle running control system according to claim 8, wherein the
first speed condition correcting unit and the second speed condition
correcting unit correct the speed of one of the adjacent regions to a
lower speed, so that the addition vector does not go beyond the friction
circle of each of the regions.

11. The vehicle running control system according to claim 4, wherein:the
first speed condition correcting unit and the second speed condition
correcting unit calculate a rate of change of acceleration across
adjacent ones of the regions; andthe first speed condition correcting
unit and the second speed condition correcting unit compare the rate of
change of acceleration with a predetermined limit value, and correct a
speed.

12. The vehicle running control system according to claim 5, wherein:the
first speed condition correcting unit and the second speed condition
correcting unit calculate a rate of change of acceleration across
adjacent ones of the regions; andthe first speed condition correcting
unit and the second speed condition correcting unit compare the rate of
change of acceleration with a predetermined limit value, and correct a
speed.

13. The vehicle running control system according to claim 11, wherein,
when changes in the speed over adjacent ones of the regions assume a
concave shape, the first speed condition correcting unit and the second
speed condition correcting unit correct the speed condition of one of the
adjacent regions having the highest speed and located at the leading side
as viewed in a direction of progression of the speed correction, to a
lower speed.

14. The vehicle running control system according to claim 12, wherein,
when changes in the speed over adjacent ones of the regions assume a
concave shape, the first speed condition correcting unit and the second
speed condition correcting unit correct the speed condition of one of the
adjacent regions having the highest speed and located at the leading side
as viewed in a direction of progression of the speed correction, to a
lower speed.

15. The vehicle running control system according to claim 11, wherein,
when changes in the speed over adjacent ones of the regions assume a
convex shape, the first speed condition correcting unit and the second
speed condition correcting unit correct the speed condition of a middle
one of the regions having the highest speed, to a lower speed.

16. The vehicle running control system according to claim 12, wherein,
when changes in the speed over adjacent ones of the regions assume a
convex shape, the first speed condition correcting unit and the second
speed condition correcting unit correct the speed condition of a middle
one of the regions having the highest speed, to a lower speed.

17. The vehicle running control system according to claim 11, wherein the
limit value is set according to a shape of the target traveling path.

18. The vehicle running control system according to claim 12, wherein the
limit value is set according to a shape of the target traveling path.

19. The vehicle running control system according to claim 1, wherein the
first speed condition correcting unit and the second speed condition
correcting unit correct the speed conditions while regarding the vehicle
as a mass point model.

20. The vehicle running control system according to claim 19, wherein the
first speed condition correcting unit and the second speed condition
correcting unit correct lateral force conditions while regarding the
vehicle as a rigid body model, after completing the speed correction of
the speed condition for each of the regions into which the target
traveling path is divided.

21. The vehicle running control system according to claim 1, further
comprising a traveling path dividing unit that divides the speed pattern
into a plurality of regions corresponding to running conditions,wherein
the running control unit performs assist control for assisting in
accomplishing a traveling plan, with respect to each of the regions into
which the speed pattern is divided.

22. The vehicle running control system according to claim 21, further
comprising an evaluation display unit that outputs information concerning
the running conditions corresponding to the regions and/or information
concerning a deviation between a controlled variable associated with the
speed in the speed pattern and a controlled variable associated with the
speed entered by the driver to the vehicle, such that the information is
visually and/or audibly recognizable.

Description:

INCORPORATION BY REFERENCE

[0001]The disclosure of Japanese Patent Application No. 2009-116487 filed
on May 13, 2009 and Japanese Patent Application No. 2010-39340 filed on
Feb. 24, 2010 each including the specification, drawings and abstract is
incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]The invention relates to a vehicle running control system that
creates a traveling path along which the vehicle is going to run, creates
a speed pattern according to the traveling path, and controls running of
the vehicle based on the traveling path and the speed pattern.

[0004]2. Description of the Related Art

[0005]A technology of creating the optimum traveling track of the vehicle
and automatically running the vehicle using the traveling track has been
developed. An example of the technology is described in a paper on
"Numerical Analysis of Minimum-Time Cornering Method (Takehiko Fujioka,
Daisuke. Emori: JSAE (Society of Automotive Engineers of Japan) papers,
Vol. 24, No. 3, July 1993, p 106-p 111)". This paper is concerned with a
method of calculating an ideal track utilizing an optimization method, in
which a length of time required to pass a corner is set as an evaluation
function, and the ever-changing position and speed of the vehicle are
calculated using the optimization method so that the evaluation function
is minimized, so as to create a traveling track and a speed pattern which
enable the vehicle to pass the corner in the minimum time.

[0006]In the technology of the above-identified paper, the position
(track) and speed of the vehicle are changed, and evaluation functions
are based on convergent calculations that are repeatedly performed while
monitoring changes in the position and speed; therefore, when highly
accurate traveling track and speed pattern of the vehicle are to be
created, the number of calculations is increased, and the calculation
time is prolonged. Therefore, a highly accurate, expensive control system
needs to be installed on the vehicle.

[0007]Also, Japanese Patent Application Publication No. 2006-327545
(JP-A-2006-327545) discloses a system that sets sections for a target
track (all of the sections) in a traveling plan of a mobile unit
including a vehicle, and sets constraints to movement for each section,
so as to improve a traveling result when the vehicle runs over all of the
sections.

[0008]However, the system of JP-A-2006-327545 does not take account of how
vehicle control based on a target speed pattern and driver's operations
are coordinated, so as to make the actual speed pattern close to the
target speed pattern, while meeting with the requested acceleration
entered through the actual operation of the driver. Thus, there is room
for improvement in coordinating vehicle control based on a traveling plan
and driver's operations with further improved efficiency.

[0009]More specifically, typical examples of assist systems for improved
fuel efficiency include, for example, "ECO MODE" of Toyota Motor
Corporation, "ECON" of Honda Motor Co., Ltd., and "SI-DRIVE" of Fuji
Heavy Industries Ltd. The respective systems of these companies are
operable to change the accelerator pedal input in the form of depression
of the accelerator pedal by the driver, by a moderate degree, for
improvement in the fuel efficiency or fuel economy. Also, these systems
are configured such that the driver makes a mode selection by means of,
for example, a switch (SW).

[0010]However, these systems regard driver's operations as predominant
inputs (true answers), and is not able to determine whether an input in
the form of a driver's operation on the accelerator pedal or brake pedal
is unnecessary or useless. In these systems, therefore, the inputs in the
form of driver's operations are kept being predominant, and the control
side provides only limited assistance for improvement of the fuel
efficiency. Consequently, these systems can improve the fuel efficiency
only by about 5% (a nominal value), and have difficulty in achieving a
significant improvement in the fuel efficiency.

SUMMARY OF THE INVENTION

[0011]The invention provides a vehicle running control system that creates
a speed pattern according to a traveling path within a short time, and
permits appropriate running control of the vehicle based on the speed
pattern.

[0012]The invention also provides a vehicle running control system that
coordinates vehicle control based on a traveling plan and driver's
operations with improved efficiency, so that the traveling plan can be
accomplished with increased reliability.

[0013]One aspect of the invention is concerned with a vehicle running
control system. The vehicle running control system includes a speed
pattern creating unit that creates a speed pattern according to a target
traveling path, a running control unit that controls running of the
vehicle based on the speed pattern, a first speed condition correcting
unit that corrects speed conditions in a direction from a start position
of the running control toward an end position of the running control on
the target traveling path, and a second speed condition correcting unit
that corrects speed conditions in a direction from the end position of
the running control toward the start position of the running control on
the target traveling path.

[0014]According to the above aspect of the invention, the vehicle running
control system is provided with the first speed condition correcting unit
that corrects speed conditions in the direction from the start position
of running control to the end position of running control on the target
traveling path, and the second speed condition correcting unit that
corrects speed conditions in the direction from the end position of
running control to the start position of running control on the target
traveling path. Therefore, the system creates the speed pattern according
to the traveling path within a short time, and permits appropriate
running control of the vehicle based on the speed pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]The foregoing and further objects, features and advantages of the
invention will become apparent from the following description of
preferred embodiments with reference to the accompanying drawings,
wherein like numerals are used to represent like elements and wherein:

[0016]FIG. 1 is a schematic view showing the configuration of a vehicle
running control system according to a first embodiment of the invention;

[0017]FIG. 2 is a flowchart illustrating a process of creating a speed
pattern according to a traveling path, which is executed by the vehicle
running control system of the first embodiment;

[0018]FIG. 3 is a schematic view useful for explaining the process of
creating a speed pattern;

[0019]FIG. 4 is a schematic view showing a traveling course of the
vehicle;

[0020]FIG. 5 is a graph indicating a speed pattern during regular circle
cornering on the traveling course;

[0021]FIG. 6 is a graph indicating a speed pattern obtained by making
acceleration correction to the speed pattern of regular circle cornering
on the traveling course;

[0022]FIG. 7 is a graph indicating a speed pattern obtained by making
acceleration correction and deceleration correction to the speed pattern
of regular circle cornering on the traveling course;

[0023]FIG. 8A is an explanatory view showing acceleration correction made
to a speed pattern of regular circle cornering;

[0024]FIG. 8B is an explanatory view showing speed patterns before and
after acceleration correction is made;

[0025]FIG. 9 is a flowchart illustrating a process of creating a speed
pattern according to a traveling path, which is executed by a vehicle
running control system according to a second embodiment of the invention;

[0026]FIG. 10A is a flowchart illustrating a process of creating a speed
pattern according to a traveling path, which is executed by a vehicle
running control system according to a third embodiment of the invention;

[0027]FIG. 10B is a flowchart illustrating the process of creating a speed
pattern according to a traveling path, which is executed by the vehicle
running control system according to the third embodiment of the
invention;

[0028]FIG. 11 is a graph indicating a speed pattern to which jerk
correction is made on the traveling course;

[0029]FIG. 12A is an explanatory view showing jerk correction made to the
speed pattern;

[0030]FIG. 12B is an explanatory view showing jerk correction made to the
speed pattern;

[0031]FIG. 13 is a flowchart illustrating a process of creating a speed
pattern according to a traveling path, which is executed by a vehicle
running control system according to a fourth embodiment of the invention;

[0032]FIG. 14 is a flowchart illustrating a process of creating a speed
pattern according to a traveling path, which is executed by a vehicle
running control system according to a fifth embodiment of the invention;

[0033]FIG. 15 is a view showing the arrangement of ECU and other
components of a vehicle running control system according to a sixth
embodiment of the invention;

[0034]FIG. 16 is a schematic view showing one example of target speed
pattern;

[0035]FIG. 17 is a schematic view showing one example of acceleration
region and coasting region;

[0036]FIG. 18 is a view showing one example of the relationship between
regions and assist control;

[0037]FIG. 19A and FIG. 19B are views showing one example of region
indicators;

[0038]FIG. 20A and FIG. 20B are views showing one example of evaluation
indicator;

[0039]FIG. 21 is a flowchart illustrating one example of main operation;

[0040]FIG. 22 is a flowchart illustrating one example of region display
operation; and

[0041]FIG. 23 is a flowchart illustrating one example of evaluation point
display operation.

DETAILED DESCRIPTION OF EMBODIMENTS

[0042]Some embodiments of the invention in the form of vehicle running
control systems will be described in detail with reference to the
drawings. It is, however, to be understood that the invention is not
limited to these embodiments.

[0043]FIG. 1 is a schematic view showing the configuration of a vehicle
running control system 1 according to a first embodiment of the
invention, and FIG. 2 is a flowchart illustrating a process according to
which the vehicle running control system 1 of the first embodiment
creates a speed pattern according to a traveling path, while FIG. 3 is a
schematic view useful for explaining the process of creating a speed
pattern. FIG. 4 is a schematic view showing a traveling course of the
vehicle, and FIG. 5 is a graph indicating a speed pattern during regular
circle cornering on the traveling course, while FIG. 6 is a graph
indicating a speed pattern obtained by making acceleration correction to
the speed pattern of regular circle cornering on the traveling course.
FIG. 7 is a graph indicating a speed pattern obtained by making
acceleration correction and deceleration correction to the speed pattern
of regular circle cornering on the traveling course, and FIG. 8A is a
view useful for explaining acceleration correction made to a speed
pattern of regular circle cornering, while FIG. 8B is a view useful for
explaining speed patterns before and after acceleration correction is
carried out.

[0044]In the vehicle running control system 1 of this embodiment, a brake
pedal sensor 11, an accelerator pedal sensor 12, a steering angle sensor
13, a G (acceleration) sensor 14, a yaw rate sensor 15, wheel speed
sensors 16, a road marking recognition sensor 17, and a navigation system
18 are connected to an electronic control unit (ECU) 10, as shown in FIG.
1.

[0045]The brake pedal sensor 11 detects the amount of depression (brake
pedal stroke or pedal effort) of the brake pedal depressed by the driver,
and outputs the detected amount of depression of the brake pedal to the
ECU 10. The accelerator pedal sensor 12 detects the amount of depression
(accelerator pedal position) of the accelerator pedal depressed by the
driver, and outputs the detected amount of depression of the accelerator
pedal to the ECU 10. The steering angle sensor 13 detects the steering
angle of the steering wheel operated by the driver, and outputs the
detected steering angle to the ECU 10.

[0046]The G (acceleration) sensor 14 detects the longitudinal acceleration
and lateral acceleration applied to the vehicle, and outputs each of the
detected accelerations to the ECU 10. The yaw rate sensor 15 detects the
yaw rate (lateral turning speed) generated in the vehicle, and outputs
the detected yaw rate to the ECU 10. The wheel speed sensor 16, which is
provided for each of the four wheels of the vehicle, detects the
rotational speed of each wheel, and outputs the detected rotational speed
of each wheel to the ECU 10. The ECU 10 calculates the vehicle speed V
based on the rotational speeds of the respective wheels.

[0047]The road marking recognition sensor 17, which has a camera and an
image processing device, detects right and left road lines located at the
opposite sides of a lane on which the vehicle is running, and outputs the
positions (coordinates) of the detected right and left road lines to the
ECU 10. The ECU 10 calculates a line (centerline) that passes the center
of the vehicle, the radius of curvature of the centerline, and so forth,
based on the positions of the road lines. The navigation system 18 is
configured to detect the current position of the vehicle, and guide the
driver to a destination along a certain path, for example. In particular,
the navigation system 18 reads the shape of the road on which the vehicle
is currently running, from a map database, and outputs the road shape
information to the ECU 10.

[0048]Also, a throttle actuator 21, a brake actuator 22, and a steering
actuator 23 are connected to the ECU 10.

[0049]The throttle actuator 21 is operable to open and close a throttle
valve of an electronic throttle device, and adjust the throttle opening.
The ECU 10 operates the throttle actuator 21 according to an engine
control signal, so as to adjust the opening of the throttle valve. The
brake actuator 22 is operable to adjust control oil pressures applied to
wheel cylinders provided in a brake system. The ECU 10 operates the brake
actuator 22 according to a brake control signal, so as to adjust the
brake pressures of the wheel cylinders. The steering actuator 22 is
operable to apply rotary driving force generated by a motor, as steering
torque, to a steering mechanism via a speed reduction mechanism. The ECU
10 operates the steering actuator 23 according to a steering control
signal, so as to adjust the steering torque by means of the motor.

[0050]When the vehicle is caused to automatically run along a road of a
certain shape, the ECU 10 needs to set a target traveling path according
to the road shape, in view of the fuel efficiency, time required to pass
the path, safety, etc., and also needs to set a speed pattern. In this
case, the target traveling path is a traveling path along which the
vehicle is expected to run. In the case where the target traveling path
includes one or more curved portions (target curved paths), information
or data concerning the target traveling path includes a large number of
parameters, such as the position of the vehicle, vehicle speed,
acceleration, and yaw rate, which are necessary to run the vehicle.

[0051]The vehicle running control system 1 of the first embodiment has a
standard speed pattern creating unit that creates a speed pattern
(regular circle maximum speed pattern) that is normally created, a
control unit that controls running of the vehicle based on the speed
pattern, a first speed condition correcting unit that performs an
operation to correct speed conditions in the speed pattern, from a start
position at which running control is started to an end position at which
the running control is finished, on the target traveling path, and a
second speed condition correcting unit that performs an operation to
correct speed conditions in the speed pattern, from the end position of
running control to the start position of running control on the target
traveling path. Namely, the first speed condition correcting unit, when
performing the correcting operation, sequentially corrects speed
conditions in the order in which they appear in the speed pattern as
viewed in a direction from the start position of this operation toward
the end position, on the target traveling path. Also, the second speed
condition correcting unit, when performing the correcting operation,
sequentially corrects speed conditions in the order in which they appear
in the speed pattern as viewed in a direction from the end position of
this operation toward the start position, on the target traveling path.

[0052]The first speed condition correcting unit corrects speed conditions
that represent or provide accelerations (which may also be called
"acceleration-side speed conditions"), and the second speed condition
correcting unit corrects speed conditions that represent or provide
decelerations (which may also be called "deceleration-side speed
conditions"). In this case, the first speed condition correcting unit and
second speed condition correcting unit correct appropriate ones of the
speed conditions to lower speeds.

[0053]Also, the vehicle running control system 1 of the first embodiment
includes a traveling path dividing unit that divides the target traveling
path into a plurality of regions at evenly spaced (distance or time)
intervals, and the first speed condition correcting unit and second speed
condition correcting unit performs a correcting operation on a speed
condition for each of the regions into which the target traveling path is
divided. More specifically, each of the first and second speed condition
correcting units compares speed conditions of adjacent ones of the
regions, and corrects the speed condition of the higher-speed region to a
lower speed.

[0054]More specifically, the first speed condition correcting unit
performs a speed-condition correcting operation for each of the regions
into which the target traveling path is divided, by calculating an
acceleration across adjacent ones of the regions, and correcting an
appropriate one of the speed conditions to a lower speed so as to prevent
the acceleration from exceeding the upper limit. On the other hand, the
second speed condition correcting unit performs a speed-condition
correcting operation for each of the regions into which the target
traveling path is divided, by calculating a deceleration across adjacent
ones of the regions, and correcting an appropriate one of the speed
conditions to a lower speed so as to prevent the deceleration from
exceeding the upper limit.

[0055]In this embodiment, the ECU 10 functions as the above-mentioned
standard speed pattern creating unit, the first speed condition
correcting unit, and the second speed condition correcting unit, and
performs various operations as described below.

[0056]The vehicle running control system 1 of the first embodiment will be
described more specifically. In the field of the running control
mechanics of the vehicle, the following general formula (equation of
motion) is established:

V2=Ay×R=μ×g×R

where V is the speed of the vehicle, V2 is the maximum speed of the
vehicle, Ay is the lateral acceleration of the vehicle, g is the
gravitational acceleration, μ is the coefficient of friction between
tires and a road surface, and R is the turning radius of the road.

[0057]The ECU 10 of the vehicle running control system 1 of the first
embodiment creates a traveling path along which the vehicle is going to
run, and also creates a speed pattern according to the traveling path,
using the above-indicated equation of motion as a precondition, in order
to keep safety within friction circles of the tires.

[0058]Initially, the ECU 10 causes the navigation system 18 to read the
road shape of a course along which the vehicle is going to run, from a
map database, and sets a target traveling path. Then, the target
traveling path is divided into a plurality of regions at fixed
infinitesimal intervals (of distance). In this case, after creating a
speed pattern according to the traveling path, the ECU 10 may divide the
target traveling path into a plurality of regions at fixed infinitesimal
intervals (of time), and perform operations as described later.

[0059]Then, the ECU 10 calculates the turning radius R of the road, in
each of the regions into which the target traveling path is divided at
the fixed infinitesimal intervals, and calculates the maximum speed of
the vehicle running in each region according to the above-described
precondition (equation of motion), using the turning radius R and the
coefficient of friction μ between the tires and the road surface.
Then, the ECU 10 creates a steady-state circle maximum speed pattern,
using a plurality of maximum speeds obtained with respect to the
respective regions into which the target traveling path is divided. In
this case, the coefficient of friction μ may be estimated based on
information obtained from the navigation system 18.

[0060]Once the steady-state circle maximum speed pattern of the target
traveling path is created, the ECU 10 calculates an acceleration across
adjacent points set in sequence in a direction from a running start point
at which the vehicle starts running to a running end point at which the
vehicle finishes running. If the acceleration exceeds the upper limit,
the ECU 10 corrects the speed of one of the points having the higher
speed and located closer to the running end point, to a lower speed, so
that the acceleration becomes equal to or smaller than the upper-limit
acceleration. In this case, the upper-limit acceleration is set to the
lower one of a value obtained from the running performance of the vehicle
and a value that causes the vehicle (tire) to go beyond the friction
circle.

[0061]Also, the ECU 10 calculates a deceleration across adjacent points
set in sequence in a direction from the running end point to the running
start point. If the deceleration exceeds the upper limit, the ECU 10
corrects the speed of one of the points having the higher speed and
located closer to the running start point, to a lower speed, so that the
deceleration becomes equal to or smaller than the upper-limit
deceleration. In this case, the upper-limit deceleration is set to the
lower one of a value obtained from the running performance of the vehicle
and a value that causes the vehicle (tire) to go beyond the friction
circle.

[0062]In the above manner, corrections of the maximum speeds according to
the accelerations and decelerations are made to the steady-state circle
maximum speed pattern, between the running start point and the running
end point, so that a speed pattern corresponding to the target traveling
is created.

[0063]A process of creating the speed pattern according to the traveling
path, which is carried out by the vehicle running control system 1 of the
first embodiment, will be described in detail, with reference to the
flowchart of FIG. 2.

[0064]In the process of creating the speed pattern according to the
traveling path, the ECU 10 of the vehicle running control system 1 of the
first embodiment creates a map of the upper-limit acceleration relative
to the speed according to the specifications of the vehicle, for the set
target traveling path, in step S11 as shown in FIG. 2. In step S12, the
ECU 10 sets the coefficient of friction μ between the tires and the
road surface. In this case, μ is set to, for example, 0.6, when the
road surface is that of an ordinary road. If it is determined in step S13
that snow accumulates on the road, or the road is an icy, low μ road,
μ is set to, for example, 0.2 in step S14.

[0065]In step S15, the ECU 10 divides the target traveling path into a
plurality of regions at fixed infinitesimal distance intervals (e.g., 1
m). Then, the ECU 10 creates an array of coordinates of respective points
placed in the plurality of regions into which the target traveling path
is divided. In this case, the running start point is expressed as a point
of coordinates (0, 0), and a point that is spaced on the north apart from
the start point by x(m) and spaced on the east apart from the start point
by y(m) is expressed as a point of coordinates (x, y). A typical point of
each of the regions, for example, a center point in each of the regions
or an average of two or more points, is represented by a point on the
coordinate system. The target traveling path is presumed to be prepared
as an array or arrangement of coordinates (x, y) that are discretely
arranged at uneven intervals. In this case, generally known linear
interpolation is performed at certain distance intervals. The calculation
results of linear interpolation involve errors if the distance between
adjacent points is largely different from one location to another when
data of the adjacent points is processed. Thus, if the distance between
points in the vicinity of the point in question is substantially equal,
different distance intervals in regions that are spaced by a great
distance (e.g., 10 m) apart from the point do not much matter.

[0066]More specifically, the ECU 10 sets a target traveling path B with
respect to a certain curved road A, as shown in FIG. 3. Then, the ECU 10
divides the target traveling path B at fixed infinitesimal intervals
along the longitudinal direction of the curved road A, so as to define a
plurality of regions C. In this case, an intersection point of the target
traveling path B and the first division line is defined as a running
start point, and an intersection point of the target traveling path B and
the last division line is defined as a running end point. Also, an
interval or distance between points of intersection between the target
traveling path B and each of the regions into which the curved road is
divided between the running start point and the running end point is
defined as a distance L between two points as described later.

[0067]Subsequently, in step S16, the ECU 10 creates a plurality of arrays
of the turning radius R (not shown) relative to the distance from the
running start point and the distance interval, in the above-indicated
plurality of regions C into which the target traveling path is divided.
In this case, the turning radius R may be calculated by a generally
known, mathematical calculation method for obtaining the radius of a
circle that passes three points. However, since data acquired from the
navigation system 18 of the vehicle includes noise, the three points used
for the above calculation may not be located adjacent to each other, but
may be appropriately spaced (by, for example, 10 m) from each other.

[0068]Then, in step S17, the ECU 10 calculates the maximum speed V of the
vehicle in each of the division regions C according to the equation of
motion, using the turning radius R of the road, and the coefficient μ
of friction between the tires and the road surface. At the running start
point and the running end point, the maximum speeds V are set as the
initial speed and the final speed, respectively. If the ECU 10 determines
in step S18 that the maximum speed V of the vehicle has been calculated
with respect to all of the division regions C of the target traveling
path, the ECU 10 creates a steady-state circle maximum speed pattern in
step S19.

[0069]Namely, a steady-state circle maximum speed pattern as shown in FIG.
5 is created with respect to a traveling course as shown in FIG. 4. The
steady-state maximum speed pattern indicates the maximum speed V in
relation to the distance to be traveled from the start point.

[0070]In steps S20 to S26, the ECU 10 corrects the maximum speed V based
on the acceleration across adjacent points set in sequence in a direction
from the running start point to the running end point, with respect to
the steady-state circle maximum speed pattern of the target traveling
path created in step S19. Namely, the ECU 10 sets a region C that is
advanced by one region from the running start point toward the running
end point in step S20. In step S21, the ECU 10 calculates a pass time
dtn from the distance Ln between two points of the maximum
speed Vn of this region Cn (running start point+1) and the
maximum speed Vn-1 of the region Cn-1 located ahead of the
region Cn, according to the following equation.

dtn=Ln/((Vn-1+Vn)/2)

Subsequently, the acceleration An at this time is calculated
according to the following equation.

An=(Vn-Vn-1)/dtn

[0071]In step S22, the ECU 10 extracts the upper-limit acceleration
Amax1 corresponding to the maximum speed Vn-1 from a map
(maximum speed-upper-limit acceleration map set in accordance with the
vehicle performance), and also calculates the maximum acceleration
Amax2 (coefficient of friction μ×gravitational acceleration
g) corresponding to the coefficient of friction μ. Here, the lower
numerical value of the upper-limit acceleration Amax1 and the
maximum acceleration Amax2 is set to the upper-limit acceleration
Amax, as indicated by the following equation.

Amax=min(Amax1, Amax2)

[0072]In step S23, the ECU 10 determines whether the acceleration An
is equal to or smaller than the upper-limit acceleration Amax. If it
is determined in step S23 that the acceleration An is equal to or
smaller than the upper-limit acceleration Amax, the control proceeds
to step S25. If it is determined in step S23 that the acceleration
An is larger than the upper-limit acceleration Amax, the ECU 10
corrects the maximum speed Vn in step S24, according to the
following equation.

Vn(Vn-1+Amax×dtn)

Namely, if the acceleration exceeds the upper limit, the ECU 10 corrects
the speed at one of the two adjacent points having the higher speed and
located closer to the running end point, to a lower speed, so that the
acceleration across the region C between the two points becomes equal to
or lower than the upper-limit acceleration.

[0073]In step S25, the ECU 10 determines whether the operation to correct
the maximum speed Vn is completed over a range from a point following the
running start point to a point ahead of the running end point. If it is
determined in step S25 that the operation to correct the maximum speed Vn
has not been completed with respect to all of the regions C, the ECU 10
sets the region C to a region that is advanced by one region toward the
running end point from the region (or point) on which the correcting
operation has been performed, and the process of steps S21 to S24 is
repeated. Then, if it is determined in step S25 that the operation to
correct the maximum speed Vn is completed over the range from the
point following the running start point to the point ahead of the running
end point, the control proceeds to step S27.

[0074]The operation to correct the maximum speed Vn from the running
start point toward the running end point will be described in detail.
When the location (point) of the maximum speed Vn and the location
(point) of the maximum speed Vn-1 ahead of that of the maximum speed
Vn are set as shown in FIG. 8A, the distance between these two
points is denoted as Ln. At this time, pass time dtn it takes
to pass the distance Ln between the point of the maximum speed
Vn and the point of the maximum speed Vn-1 is obtained, and the
acceleration An of the vehicle at this time is calculated. Then, if
the acceleration An is larger than the upper-limit acceleration
Amax, the ECU 10 corrects the maximum speed Vn. In this case,
the ECU 10 corrects the maximum speed Vn at the point having the
higher speed and located closer to the running end point, to a lower
speed. By repeatedly performing the operation to correct the maximum
speed Vn with respect to the respective regions C, variations in the
maximum speed Vn are reduced in the maximum speed pattern, as shown
in FIG. 8B.

[0075]If the operation to correct the maximum speed Vn in the
direction from the running start point toward the running end point is
performed on the steady-state circle maximum speed pattern, the
acceleration-side vehicle speed in each region C is corrected, on each
curved road, as indicated by a thick line in FIG. 6.

[0076]In steps S27 to S33, the ECU 10 corrects the maximum speed Vn
based on the deceleration across adjacent points set in sequence in a
direction from the running end point to the running start point, with
respect to the steady-state circle maximum speed pattern of the target
traveling path. Namely, the ECU 10 sets a region C that is retracted by
one region from the running end point toward the running start point in
step S27. In step S28, the ECU 10 calculates a pass time dtn from
the distance Ln between two points of the maximum speed Vn of
this region Cn (the running end point-1) and the maximum speed
Vn+1 of the region Cn+1 located ahead of the region Cn,
according to the following equation.

dtn=Ln/((Vn+Vn+1)/2)

Subsequently, the deceleration An at this time is calculated
according to the following equation.

[0078]In step S30, the ECU 10 determines whether the deceleration An
is equal to or larger than the upper-limit deceleration Amax. If it
is determined that the deceleration An is equal to or larger than
the upper-limit deceleration Amax, the control proceeds to step S32.
If it is determined that the deceleration An is smaller than the
upper-limit deceleration Amax, the ECU 10 corrects the maximum speed
Vn in step S31 according to the following equation.

Vn=(Vn+1+Amax×dtn)

Namely, if the deceleration exceeds the upper limit, the ECU 10 corrects
the speed at the point having the higher speed and located closer to the
running start point, to a lower speed, so that the deceleration becomes
equal to or smaller than the upper-limit deceleration.

[0079]In step S32, the ECU 10 determines whether the operation to correct
the maximum speed Vn is completed over a range from a point located
ahead of the running end point to a point following the running start
point. If it is determined in this step that the operation to correct the
maximum speed Vn has not been completed with respect to all of the
regions, the ECU 10 sets the region C to a region that is retracted by
one region from the region (or point) on which the correcting operation
has been performed toward the running start point in step S33, and the
process of steps S28 to S31 is repeated. Then, if it is determined in
step S32 that the operation to correct the maximum speed Vn is
completed over the range from the point ahead of the running end point to
the point following the running start point, the control proceeds to step
S34.

[0080]If the operation to correct the maximum speed Vn in the
direction from the running end point toward the running start point is
performed on the steady-state circle maximum speed pattern, the
deceleration-side vehicle speed in each region C is adequately corrected,
on each curved road, as indicated by a thick line in FIG. 7.

[0081]In step S34, the ECU 10 determines whether fixed time interval
processing is completed. If the ECU 10 determines in this step that the
fixed time interval processing has not been completed, the ECU 10 divides
the target traveling path into a plurality of regions C at fixed or
evenly spaced infinitesimal time intervals in step S35. Then, the ECU 10
creates an array of coordinates of respective points placed in the
plurality of regions C into which the target traveling path is divided.
Subsequently, in step S36, the ECU 10 creates a plurality of arrays of
the turning radius R relative to the time from the running start point
and the time interval, in the plurality of regions C into which the
target traveling path is divided.

[0082]Although not illustrated in FIG. 2, after execution of step S36, the
operation to calculate the maximum speed V of the vehicle in each
division region according to the equation of motion, using the turning
radius R of the road and the coefficient of friction μ between the
tires and the road surface, as in step S17 as described above, the
operation to determine whether the maximum speed V of the vehicle has
been calculated for all of the division regions of the target traveling
path in step S18, and the operation to create a steady-state circle
maximum speed pattern in step S19 are performed.

[0083]Subsequently, the ECU 10 calculates an acceleration across two
adjacent points set in sequence in a direction from the running start
point to the running end point, with respect to the created steady-state
circle maximum speed pattern of the target traveling path, in similar
manners to those of steps S20-S26. Then, in similar manners to those of
steps S27-S33, the ECU 10 calculates a deceleration across two adjacent
points set in sequence in a direction from the running end point to the
running start point, with respect to the steady-state circle maximum
speed pattern of the target traveling path.

[0084]Subsequently, the ECU 10 determines in step S34 whether the fixed
time interval processing is completed. If the ECU 10 determines that the
fixed time interval processing is completed, the process of FIG. 2 ends.
The ECU 10 may repeatedly perform the fixed time interval processing a
plurality of time as needed.

[0085]The vehicle running control system 1 of the first embodiment is
configured to create a speed pattern according to the target traveling
path, and control running of the vehicle based on the speed pattern, and
includes the first speed condition correcting unit that performs an
operation to correct speed conditions from the start position of running
control toward the end position of running control on the target
traveling path, and the second speed condition correcting unit that
performs an operation to correct speed conditions from the end position
of running control toward the start position of running control on the
target traveling path.

[0086]Accordingly, the vehicle running control system 1 corrects speed
conditions from the start position to the end position of running control
on the target traveling path, and also corrects speed conditions from the
end position to the start position of running control, without using the
optimization method, so as to create a speed pattern corresponding to the
traveling path within a short time, and permit adequate running control
of the vehicle based on the speed pattern.

[0087]In the vehicle running control system 1 of the first embodiment, the
ECU 10 serving as the first speed condition correcting unit and the
second speed condition correcting unit performs an operation to correct
acceleration-side speed conditions, and also performs an operation to
correct deceleration-side speed conditions. In this case, the ECU 10
corrects the speed conditions to lower speeds. Thus, the processing can
be simplified by performing the operation to correct acceleration-side
speed conditions and the operation to correct deceleration-side speed
conditions independently of each other, and correcting the speed
conditions to lower speeds.

[0088]The vehicle running control system 1 of the first embodiment
includes the traveling path dividing unit that divides the target
traveling path into a plurality of regions C at fixed or given intervals,
and the ECU 10 performs an operation to correct a speed condition for
each of the regions C, compares the speed conditions of adjacent ones of
the regions C, and corrects the speed condition of the higher-speed
region C to a lower speed. In this case, the ECU 10 compares the speeds
of the adjacent regions C, and performs a correcting operation so as to
prevent the acceleration or deceleration from exceeding the upper limit.
Thus, the target traveling path is divided into a plurality of regions at
fixed intervals, and the operation to correct the speed condition to a
lower speed is performed for each of the regions C, so that the speed
conditions can be corrected with high accuracy.

[0089]In the first embodiment as described above, with respect to the
steady-state circle maximum speed pattern of the target traveling path,
the acceleration across adjacent points set in sequence in a direction
from the running start point to the running end point is calculated, and
then the deceleration across adjacent points set in sequence in a
direction from the running end point to the running start point is
calculated. However, with respect to the steady-state circle maximum
speed pattern of the target traveling path, the deceleration across
adjacent points set in sequence in a direction from the running end point
to the running start point may be first calculated, and then the
acceleration across adjacent points set in sequence in a direction from
the running start point to the running end point may be calculated.

[0090]FIG. 9 is a flowchart illustrating a process of creating a speed
pattern according to a traveling path, which is executed by a vehicle
running control system 1 according to a second embodiment of the
invention. The overall configuration of the vehicle running control
system 1 of this embodiment is substantially the same as that of the
first embodiment as described above, and will be described with reference
to FIG. 1. Also, the same reference numerals as used in the first
embodiment are assigned to members or components having the same or
similar functions as those of the first embodiment, and explanation of
these members or components will not be repeated.

[0091]In the vehicle running control system 1 of the second embodiment,
the first speed condition correcting unit and the second speed condition
correcting unit calculate an addition vector of the acceleration or
deceleration across adjacent regions C and the lateral acceleration, and
performs a speed correcting operation based on the addition vector and a
friction circle set for each region. More specifically, the first speed
condition correcting unit and second speed condition correcting unit
correct the speeds of the adjacent regions to lower speeds, so that the
addition vector does not go beyond the friction circle of each region.

[0092]Described more specifically, the vehicle running control system 1 of
the second embodiment has a process to be carried out subsequently to the
process of creating a speed pattern in the first embodiment as described
above. Namely, if the target traveling path is a curved traveling path
along which the turning radius R changes gently or at a low rate, like an
expressway, a speed pattern can be adequately created through the speed
pattern creating process of the first embodiment. In this case, the
maximum speed changes slowly in the speed pattern. On the other hand, if
the target traveling path is a curved traveling path along which the
turning radius R abruptly changes, the acceleration or deceleration
during running along the curve increases, and addition of vectors of the
longitudinal acceleration and lateral acceleration may result in
breakdown of the friction circle. Therefore, when the sum of a vector of
acceleration or deceleration and a vector of lateral acceleration goes
beyond the friction circle, the vehicle running control system 1 of the
second embodiment reduces the acceleration or deceleration so that the
sum of the vectors falls within the friction circle.

[0093]Once a speed pattern of the target traveling path is created, as in
the first embodiment, the ECU 10 initially adds an acceleration (vector)
and a lateral acceleration (vector) across adjacent points set in
sequence in a direction from the running start point to the running end
point. If the sum of the vectors goes beyond the friction circle, the ECU
10 corrects the speed of one of the adjacent points having the higher
speed and located closer to the running end point, to a lower speed, so
that the addition vector of the accelerations lies within the friction
circle.

[0094]Also, the ECU 10 adds a deceleration (vector) and a lateral
acceleration (vector) across adjacent points set in sequence in a
direction from the running end point to the running start point. If the
sum of the vectors goes beyond the friction circle, the ECU 10 corrects
the speed of one of the adjacent points having the higher speed and
located closer to the running start point, to a lower speed, so that the
addition vector of the accelerations lies within the friction circle.

[0095]The optimum method of avoiding going beyond the friction circle,
more specifically, which of the acceleration and the lateral acceleration
is to be reduced by what degree, depends on detailed running conditions
of the vehicle, and the above-mentioned process may not be optimal. In
this embodiment, however, the speed is ultimately reduced and the lateral
vector is reduced, at adjacent points where the acceleration or
deceleration is limited. As a result, the acceleration or deceleration
across adjacent points can be reduced; therefore, a substantially optimum
speed pattern is created with respect to a target traveling path along
which the turning radius R abruptly changes, even though it is high-speed
processing.

[0096]A process of creating a speed pattern according to a traveling path,
which is executed by the vehicle running control system 1 of the second
embodiment, will be described in detail with reference to the flowchart
of FIG. 9.

[0097]In the process of creating a speed pattern according to a traveling
path with the vehicle running control system 1 of the second embodiment,
after the speed pattern creating process (the flowchart of FIG. 2) of the
first embodiment is completed, the process as shown in FIG. 9 is carried
out. In step S41 to step S48, the ECU 10 corrects the maximum speed based
on an addition vector across adjacent points set in sequence in a
direction from the running start point to the running end point, with
respect to the speed pattern of the target traveling path. Namely, the
ECU 10 sets a region that is advanced by one region from the running
start point toward the running end point in step S41, and calculates a
pass time dtn in step S42, based on a distance Ln between two
points of the maximum speed Vn of this region (the running start
point+1) Cn and the maximum speed Vn-1 of a region Cn-1
located ahead of the region Cn, according to the following equation.

dtn=Ln/((Vn-1+Vn)/2)

Then, the acceleration Axn at this time is calculated according to
the following equation.

Axn=(Vn-Vn-1)/dtn

[0098]In step S43, the ECU 10 determines whether the acceleration Axn
is equal to or smaller than 0. If it is determined in step S43 that the
acceleration Axn is equal to or smaller than 0, the control proceeds
to step S47. On the other hand, if it is determined that the acceleration
Axn is larger than 0, the ECU 10 proceeds to step S44 to extract the
turning radius R at each point, and calculate the lateral acceleration
Ayn according to the following equation.

AYn=((Vn-1+Vn)/2)2/R

Subsequently, an absolute value |A| of an acceleration addition vector is
calculated according to the following equation, by adding vectors of the
acceleration Axn and lateral acceleration Ayn together:
|A|=sqrt(Axn2+Ayn2), where sqrt represents square
root.

[0099]In step S45, the ECU 10 determines whether the absolute value |A| of
the acceleration addition vector is equal to or smaller than the maximum
acceleration Amax (coefficient of friction μ×gravitational
acceleration g) of the friction circle as the upper limit. If it is
determined in step S45 that the absolute value |A| of the acceleration
addition vector is equal to or smaller than the maximum acceleration
Amax as the upper limit, it is presumed that the acceleration will
not go beyond the friction circle, and the control proceeds to step S47.
On the other hand, if it is determined in step S46 that the absolute
value |A| of the acceleration addition vector is larger than the maximum
acceleration Amax, it is presumed that the acceleration will go
beyond the friction circle, and the ECU 10 corrects the acceleration
Axn and the maximum speed Vn in step S46, according to the
following equations.

Axn=sqrt(μ×g)2-Ayn2

Vn=(Vn-1+Axn×dtn)

Namely, when the addition vector goes beyond the friction circle, the ECU
10 corrects the speed at one of the adjacent points having the higher
speed and located closer to the running end point, to a lower speed, so
that the addition vector does not go beyond the friction circle.

[0100]The ECU 10 determines in step S47 whether the operation to correct
the maximum speed Vn is completed over a range from the point
following the running start point to a point located ahead of the running
end point. If it is determined in step S47 that the operation to correct
the maximum speed Vn has not been completed with respect to all of
the regions, the ECU 10 sets a region C that is advanced by one region
from the region (point) C that has been processed toward the running end
point, and repeats the process of steps S42 to S47. If it is determined
in step S47 that the operation to correct the maximum speed Vn is
completed over the range from the point following the running start point
to the point ahead of the running end point, the control proceeds to step
S49.

[0101]In steps S49 to S56, the ECU 10 corrects the maximum speed based on
the addition vector across adjacent points set in sequence in a direction
from the running end point toward the running start point, with respect
to the steady-state circle maximum speed pattern of the target traveling
path. Namely, the ECU 10 sets a region that is retracted by one region
from the running end point toward the running start point in step S49,
and calculates a pass time dtn in step S50, from a distance Ln
between two points of the maximum speed Vn of this region (the
running end point-1) Cn and the maximum speed Vn+1 of the
region Cn+1 located ahead of the region Cn+1, according to the
following equation.

dtn=Ln/((Vn+Vn+1)/2)

Subsequently, the deceleration Axn is calculated according to the
following equation.

Axn=(Vn+1-Vn)/dtn

[0102]In step S51, the ECU 10 determines whether the deceleration Axn
is equal to or larger than 0. If it is determined in step S51 that the
deceleration Axn is equal to or larger than 0, the control proceeds
to step S55. On the other hand, if it is determined that the deceleration
Axn is smaller than 0, the ECU 10 proceeds to step S52 to extract
the turning radius R at each point, and calculate the lateral
acceleration Ayn according to the following equation.

Ayn=((Vn+1+Vn)/2)2/R

Subsequently, an absolute value |A| of a deceleration addition vector is
calculated according to the following equation, by adding a vector of the
deceleration Axn and a vector of the lateral acceleration Ayn.

|A|=sqrt(Axn2+Ayn2)

[0103]In step S53, the ECU 10 determines whether the absolute value |A| of
the deceleration addition vector is equal to or smaller than the maximum
acceleration Amax (coefficient of friction μ×gravitational
acceleration g) of the friction circle as the upper limit. If it is
determined in step S53 that the absolute value |A| of the deceleration
addition vector is equal to or smaller than the maximum acceleration
Amax as the upper limit, it is presumed that the acceleration will
not go beyond the friction circle, and the control proceeds to step S55.
On the other hand, if it is determined that the absolute value |A| of the
deceleration addition vector is larger than the maximum acceleration
Amax, it is presumed that the acceleration will go beyond the
friction circle, and the ECU 10 corrects the deceleration Axn and
the maximum speed Vn in step S54, according to the following
equations.

Axn=sqrt(μ×g)2-Ayn2

Vn=(Vn+1+Axn×dtn)

Namely, when the addition vector goes beyond the friction circle, the ECU
10 corrects the speed at one of the adjacent points having the higher
speed and located closer to the running start point, to a lower speed, so
that the addition vector does not go beyond the friction circle.

[0104]The ECU 10 determines in step S55 whether the operation to correct
the maximum speed Vn is completed over a range from a point ahead of
the running end point to a point following the running start point. If it
is determined in step S55 that the operation to correct the maximum speed
Vn has not been completed with respect to all of the regions C, the
ECU 10 sets a region C that is retracted by one region from the region
(point) C that has been processed toward the running start point, and
repeats the process of steps S50-S55. If it is determined in step S55
that the operation to correct the maximum speed Vn is completed over
the range from the point ahead of the running end point to the point
following the running start point, the process of FIG. 9 ends.

[0105]Thus, in the vehicle running control system 1 of the second
embodiment, the ECU 10 calculates an addition vector of the acceleration
or deceleration across adjacent regions and the lateral acceleration, and
corrects the speed based on the addition vector and the friction circle
of each region C. More specifically, the ECU 10 corrects the speed of one
of the adjacent regions, to a lower speed, so that the addition vector
does not go beyond the friction circle of each region.

[0106]Accordingly, even in a region of the target traveling path in which
there are large variations in the turning radius, it is possible to
improve the safety by setting the maximum speed so as not to go beyond
the friction circle.

[0107]FIG. 10A and FIG. 10B are flowcharts illustrating a process of
creating a speed pattern according to a traveling path, which is executed
by a vehicle running control system 1 according to a third embodiment of
the invention, and FIG. 11 is a graph showing a speed pattern to which
corrections concerning jerks on a traveling course are made. FIG. 12A is
a view useful for explaining jerk correction made to the speed pattern,
and FIG. 12B is a view useful for explaining jerk correction made to the
speed pattern. The overall configuration of the vehicle running control
system 1 of this embodiment is substantially the same as that of the
first embodiment as described above, and will be described with reference
to FIG. 1. Also, the same reference numerals as used in the first
embodiment are assigned to members or components having the same or
similar functions as those of the first embodiment, and explanation of
these members or components will not be repeated.

[0108]In the vehicle running control system 1 of the third embodiment, the
first speed condition correcting unit and the second speed condition
correcting unit calculate a jerk (or rate of change of acceleration)
across adjacent regions, and compare the jerk with predetermined upper
limit and lower limit (limit values), so as to perform a speed correcting
operation.

[0109]In this case, when changes in the speed across three adjacent
regions C assume a recessed or concave shape (or a convex shape as viewed
from the top), the first speed condition correcting unit and second speed
condition correcting unit correct a speed condition of one of the regions
C having the highest speed and located at the leading side as viewed in
the direction of progression of the correcting operation, to a lower
speed. Also, when changes in the speed across three adjacent regions C
assume a convex shape (or a concave shape as viewed from the bottom), the
first speed condition correcting unit and second speed condition
correcting unit correct a speed condition of an intermediate region
having the highest speed, to a lower speed.

[0110]Described more specifically, the vehicle running control system 1 of
the third embodiment has a process to be carried out subsequently to the
process of creating a speed pattern in the first embodiment or second
embodiment as described above. Namely, the vehicle running control system
1 of the first or second embodiment regards the vehicle as one mass point
when performing the speed pattern creating process; therefore, when the
vehicle that has been fully accelerated is fully decelerated at a point
immediately ahead of a curved path, a speed pattern is created in which
the target maximum speed changes instantaneously from the maximum
acceleration to the maximum deceleration. During running of the actual
vehicle, however, the vehicle undergoes pitching if the above-described
running control is performed, and the posture of the vehicle may become
unstable or lost.

[0111]Therefore, the vehicle running control system 1 of the third
embodiment calculates the jerk (i.e., the rate of change of
acceleration), so as to take account of the maximum speed of response and
ride comfort of the vehicle, while setting the upper limit and lower
limit of the jerk, and corrects the speed pattern so that the jerk falls
within a range between the jerk upper limit and the jerk lower limit.

[0112]Once a speed pattern of the target traveling path is created, the
jerk (i.e., the rate of change of acceleration) across three points set
in sequence in a direction from the running start point to the running
end point is calculated. If the jerk exceeds the jerk upper limit, the
speed of one of the three points which is closest to the running end
point is corrected to a lower speed (i.e., reduced) so that the jerk
across the three points becomes smaller than the jerk upper limit.
Through this operation, speed correction can be made with high efficiency
in the region where changes in the speed over three points assume a
concave or recessed shape and where the acceleration across the region is
positive (+).

[0113]Also, the jerk (i.e., the rate of change of acceleration) across
three points set in sequence in a direction from the running end point to
the running start point is calculated. If the jerk exceeds the jerk upper
limit, the speed of one of the three points which is closest to the
running start point is corrected to a lower speed (i.e., reduced) so that
the jerk across the three points becomes smaller than the jerk upper
limit. Through this operation, speed correction can be made with high
efficiency in the region where changes in the speed over three points
assume a concave or recessed shape and where the acceleration across the
region is negative (-).

[0114]Subsequently, the jerk (i.e., the rate of change of acceleration)
across three adjacent points set in sequence in the direction from the
running start point to the running end point is calculated again. If the
jerk is smaller than the jerk lower limit, the speed of the middle point
of the three points is corrected to a lower speed (i.e., reduced) so that
the jerk across the three points becomes larger than the jerk lower
limit. Through this operation, speed correction can be made with high
efficiency in the region where changes in the speed over three points
assume a convex shape and where the acceleration across the region is
positive (+).

[0115]Also, the jerk (i.e., the rate of change of acceleration) across
three adjacent points set in sequence in the direction from the running
end point to the running start point is calculated. If the jerk is
smaller than the jerk lower limit, the speed of the middle point of the
three points is corrected to a lower speed (i.e., reduced) so that the
jerk across the three points becomes larger than the jerk lower limit.
Through this operation, speed correction can be made with high efficiency
in the region where changes in the speed over three points assume a
convex shape and where the acceleration across the region is negative
(-).

[0116]During the second scanning from the running start point to the
running end point and the second scanning from the running end point to
the running start point, the speed of the middle point of the three
adjacent points is corrected. Therefore, the speed of one of the three
points located at the leading end in the scanning direction, namely, the
speed of the point closest to the running start point in the scanning
from the running start point to the running end point, or the speed of
the point closest to the running end point in the scanning from the
running end point to the running start point, is not corrected. In this
case, the jerk may not become larger than the jerk lower limit through
one scanning operation. Therefore, a margin α (e.g., 10%) may be
added to the jerk lower limit, so as to speed up control of the jerk
within the above limits. Since errors are more likely to occur to highly
accurate values as the margin α is larger, it is necessary to
adequately set the margin α in view of the processing time and the
control accuracy. In some cases, the acceleration(s) resulting from the
correcting operation of this embodiment may exceed the upper-limit
acceleration used in the first embodiment; therefore, the correcting
operation of this embodiment using the jerk needs to be performed in view
of the upper-limit acceleration used in the first embodiment.

[0117]A process of creating a speed pattern according to a traveling path,
which is executed by the vehicle running control system 1 of the third
embodiment, will be described in detail with reference to the flowcharts
of FIG. 10A and FIG. 10B.

[0118]In the process of creating a speed pattern according to a traveling
path with the vehicle running control system 1 of the third embodiment,
once the speed pattern creating process (the flowchart of FIG. 2) of the
first embodiment is completed, the process as shown in FIG. 10A is
carried out. In steps S61-S69, the ECU 10 corrects the maximum speed in
the speed pattern of the target traveling path, based on the jerk across
three adjacent points set in sequence in the direction from the running
start point to the running end point. Through this operation, speed
correction can be made with high efficiency in each region where speed
changes over three points assume a concave or recessed shape and where
the acceleration across the region is negative (-).

[0119]Namely, the ECU 10 sets a region C that is advanced by one region
from the running start point toward the running end point in step S61,
and calculates pass times dt1, dt2 in step S62, based on
distances L1, L2 among the points of the maximum speed Vn
of this region Cn (the running start point+1), the maximum speed
Vn-1 of a region Cn-1 located ahead of the region Cn, and
the maximum speed Vn+1 of a region Cn+1 located behind the
region Cn, according to the following equations.

dt1=L1/((Vn-1+Vn)/2)

dt2=L2/((Vn+Vn+1)/2)

Subsequently, the accelerations A1, A2 at this time are
calculated according to the following equations.

A1=(Vn-Vn-1)/dt1

A2=(Vn+1-Vn)/dt2

Furthermore, the jerk (the rate of change of acceleration) J at this time
is calculated according to the following equation.

J=(A2-A1)/((dt1+dt2)/2)

[0120]The ECU 10 determines in step S63 whether the jerk J is equal to or
smaller than the upper-limit jerk Jmax1 (for example, 6 m/s3).
If it is determined in step S63 that the jerk J is equal to or smaller
than the upper-limit jerk Jmax1, a jerk limiting condition is
satisfied; therefore, the control proceeds to step S65. If, on the other
hand, it is determined that the jerk J is larger than the upper-limit
jerk Jmax1, the ECU 10 corrects the acceleration A2 according
to the following equation, so as to satisfy the jerk limiting condition.

A2=A1+Jmax1×((dt1+dt2)/2)

[0121]In step S65, the ECU 10 determines whether the acceleration A2
is equal to or smaller than the upper-limit acceleration Amax1
extracted from a map (indicating the relationship between the maximum
speed set in accordance with the vehicle performance and the upper-limit
acceleration). If it is determined in step S65 that the acceleration
A2 is equal to or smaller than the upper-limit acceleration
Amax1, the control proceeds to step S67. On the other hand, if it is
determined that the acceleration A2 is larger than the upper-limit
acceleration Amax1, the ECU 10 re-correct the acceleration A2
so that the upper-limit acceleration Amax1 is set as the
acceleration A2. In the case where it is impossible to achieve the
acceleration set based on the jerk, the upper-limit acceleration
Amax1 set according to the vehicle performance is prioritized over
the acceleration A2 set based on the jerk.

[0122]In step S67, the ECU 10 corrects the maximum speed Vn+1
according to the following equation.

Vn+1=Vn+A2×dt2

Namely, when the jerk exceeds the upper limit, the ECU 10 corrects the
speed of one of the three adjacent points having the highest speed and
located closest to the running end point, to a lower speed.

[0123]In step S68, the ECU 10 determines whether the operation to correct
the maximum speed Vn is completed over a range from a point
following the running start point to a point located ahead of the running
end point with two regions interposed therebetween. If it is determined
that the operation to correct the maximum speed Vn has not been
completed with respect to all of the regions, the ECU 10 sets a region C
that is advanced by one region from the region (point) that has been
processed toward the running end point in step S69, and repeats the
process of steps S62-S68. Then, if it is determined in step S68 that the
operation to correct the maximum speed Vn is completed over the
range from the point following the running start point to the point
located ahead of the running end point with two regions interposed
therebetween, the control proceeds to step S70.

[0124]The operation to correct the maximum speed by using the jerk
calculated in sequence in the direction from the running start point to
the running end point will be described in greater detail. As shown in
FIG. 12A, when a point of the maximum speed Vn, a point of the
maximum speed Vn-1 located ahead of the point of Vn, and a
point of the maximum speed Vn+1 located behind the point of Vn
are given or set, a jerk J across these three points is calculated. If
the jerk J is larger than the upper-limit jerk Jmax1, the ECU 10
corrects the maximum speed Vn+1. In this case, the ECU 10 corrects
the maximum speed Vn+1, i.e., the speed of the point having the
highest speed and located closest to the running end point, to a lower
speed.

[0125]In steps S70-S77, the ECU 10 corrects the maximum speed based on the
jerk across three adjacent points set in sequence in the direction from
the running end point to the running start point, with respect to the
speed pattern of the target traveling path. Through this operation, speed
correction can be made with high efficiency in each region where speed
changes over three points assume a concave or recessed shape and where
the acceleration across the region is negative (-).

[0126]Namely, the ECU 10 sets a region C that is retracted by one region
from the running end point toward the running start point in step S70,
and calculates pass times dt1, dt2 in step S71, based on
distances L1, L2 among the respective points of the maximum
speed Vn of this region Cn (the running end point-1), the
maximum speed Vn-1 of a region Cn+1 located ahead of the region
Cn, and the maximum speed Vn-1 of a region Cn-1 located
behind the region Cn, according to the following equations.

dt1=L1/((Vn-1+Vn)/2)

dt2=L2/((Vn+Vn+1)/2)

Subsequently, the accelerations A1, A2 at this time are
calculated according to the following equations.

A1=(Vn-Vn-1)/dt1

A2=(Vn+1-Vn)/dt2

Furthermore, the jerk (the rate of change of acceleration) J at this time
is calculated according to the following equation.

J=(A2-A1)/((dt1+dt2)/2)

[0127]The ECU 10 determines in step S72 whether the jerk J is equal to or
smaller than the upper-limit jerk Jmax1. If it is determined in step
S72 that the jerk J is equal to or smaller than the upper-limit jerk
Jmax1, the jerk limiting condition is satisfied; therefore, the
control proceeds to step S74. If, on the other hand, it is determined
that the jerk J is larger than the upper-limit jerk Jmax1, the ECU
10 corrects the acceleration A1 in step S73 according to the
following equation, so as to satisfy the jerk limiting condition.

A1=A2-Jmax1×((dt1+dt2)/2)

[0128]In step S74, the ECU 10 determines whether the acceleration A1
is equal to or smaller than the upper-limit acceleration Amax1. If
it is determined in this step that the acceleration A1 is equal to
or smaller than the upper-limit acceleration Amax1, the control
proceeds to step S76. On the other hand, if it is determined that the
acceleration A1 is larger than the upper-limit acceleration
Amax1, the ECU 10 re-correct the acceleration A1 so that the
upper-limit acceleration Amax1 is set as the acceleration A1.
In the case where it is impossible to achieve the acceleration set based
on the jerk, the upper-limit acceleration Amax1 set according to the
vehicle performance is prioritized over the acceleration A1 set
based on the jerk.

[0129]In step S76, the ECU 10 corrects the maximum speed Vn-1
according to the following equation.

Vn-1=Vn-A1×dt1

Namely, when the jerk exceeds the upper limit, the ECU 10 corrects the
speed of one of the three adjacent points having the highest speed and
located closest to the running start point, to a lower speed.

[0130]In step S77, the ECU 10 determines whether the operation to correct
the maximum speed Vn is completed over a range from the point
located ahead of the running end point to the second point as counted
from the running start point. If it is determined that the operation to
correct the maximum speed Vn has not been completed with respect to
all of the regions, the ECU 10 sets a region C that is retracted by one
region from the region (point) that has been processed toward the running
start point in step S78, and repeats the process of steps S70-S77. Then,
if it is determined in step S77 that the operation to correct the maximum
speed Vn is completed over the range from the point located ahead of
the running end point to the second point as counted from the running
start point, the control proceeds to step S79.

[0131]As shown in FIG. 10B, in steps S79-S83, the ECU 10 corrects the
maximum speed based on the jerk across three adjacent points set in
sequence in the direction from the running start point to the running end
point, with respect to the speed pattern of the target traveling path.
Through this operation, speed correction can be made with high efficiency
in each region where speed changes over three points assume a convex
shape and where the acceleration across the region is positive (+).

[0132]Namely, the ECU 10 sets a region C that is advanced by one region
from the running start point toward the running end point in step S79,
and calculates pass times dt1, dt2 in step S80, based on
distances L1, L2 among the respective points of the maximum
speed Vn of this region Cn (the running start point+1), the
maximum speed Vn-1 of a region Cn-1 located ahead of the region
Cn, and the maximum speed Vn+1 of a region Cn+1 located
behind the region Cn, according to the following equations.

dt1=L1/((Vn-1+Vn)/2)

dt2=L2/((Vn+Vn+1)/2)

Subsequently, the accelerations A1, A2 at this time are
calculated according to the following equations.

A1=(Vn-Vn-1)/dt1

A2=(Vn+1-Vn)/dt2

[0133]Furthermore, the jerk (the rate of change of acceleration) J at this
time is calculated according to the following equation.

J=(A2-A1)/((dt1+dt2)/2)

[0134]The ECU 10 determines in step S81 whether the jerk J is equal to or
larger than the lower-limit jerk Jmax2 (for example, -6 m/s3).
If it is determined in step S81 that the jerk J is equal to or larger
than the lower-limit jerk Jmax2, a jerk limiting condition is
satisfied; therefore, the control proceeds to step S83. If, on the other
hand, it is determined that the jerk J is smaller than the lower-limit
jerk Jmax2, the ECU 10 sets a margin coefficient k (e.g., 0.9) for
the jerk lower limit in step S82, so as to speed up control of the jerk J
within the limits. Then, the ECU 10 corrects the acceleration A1 and
the maximum speed Vn according to the following equations, so as to
satisfy the jerk limiting condition.

A1=(Vn+1-Vn-1)/(dt1+dt2)+Jmax2×dt1/2×k

Vn=Vn-1+A1×dt1

Namely, when the jerk is smaller than the lower limit, the ECU 10 corrects
the speed of the middle one of the three adjacent points which has the
highest speed, to a lower speed.

[0135]In step S83, the ECU 10 determines whether the operation to correct
the maximum speed Vn is completed over the range from the point
following the running start point to the point located ahead of the
running end point with two regions interposed therebetween. If it is
determined that the operation to correct the maximum speed Vn has
not been completed with respect to all of the regions, the ECU 10 sets a
region C that is advanced by one region from the region (point) C that
has been processed toward the running end point, in step S84, and repeats
the process of steps S79-S82. Then, if it is determined in step S83 that
the operation to correct the maximum speed Vn is completed over the
range from the point following the running start point to the point
located ahead of the running end point with two regions interposed
therebetween, the control proceeds to step S85.

[0136]The operation to correct the maximum speed by using the jerk
calculated in sequence in the direction from the running start point to
the running end point will be described in greater detail. As shown in
FIG. 12B, when a point of the maximum speed Vn, a point of the
maximum speed Vn-1 located ahead of the point of Vn, and a
point of the maximum speed Vn+1 located behind the point of Vn
are given or set, a jerk J across these three points is calculated. If
the jerk J is smaller than the lower-limit jerk Jmax2, the ECU 10
corrects the maximum speed Vn. In this case, the ECU 10 corrects the
maximum speed Vn, i.e., the speed of the middle point having the
highest speed, to a lower speed.

[0137]In steps S85-S89, the ECU 10 corrects the maximum speed based on the
jerk across three adjacent points set in sequence in the direction from
the running end point to the running start point, with respect to the
speed pattern of the target traveling path. Through this operation, speed
correction can be made with high efficiency in each region where speed
changes over three points assume a convex shape and where the
acceleration across the region is negative (-).

[0138]Namely, the ECU 10 sets a region C that is retracted by one region
from the running end point toward the running start point in step S85,
and calculates pass times dt1, dt2 in step S86, based on
distances L1, L2 among the respective points of the maximum
speed Vn of this region Cn (the running end point-1), the
maximum speed Vn+1 of a region Cn+1 located ahead of the region
Cn, and the maximum speed Vn-1 of a region Cn-1 located
behind the region Cn, according to the following equations.

dt1-L1/((Vn-1+Vn)/2)

dt2=L2/((Vn+Vn+1)/2)

Subsequently, the accelerations A1, A2 at this time are
calculated according to the following equations.

A1=(Vn-Vn-1)/dt1

A2=(Vn+1-Vn)/dt2

Furthermore, the jerk (the rate of change of acceleration) J at this time
is calculated according to the following equation.

J=(A2-A1)/((dt1+dt2)/2)

[0139]The ECU 10 determines in step S87 whether the jerk J is equal to or
larger than the lower-limit jerk Jmax2. If it is determined in step
S87 that the jerk J is equal to or larger than the lower-limit jerk
Jmax2, a jerk limiting condition is satisfied; therefore, the
control proceeds to step S89. If, on the other hand, it is determined
that the jerk J is smaller than the lower-limit jerk Jmax2, the ECU
10 sets a margin coefficient k (e.g., 0.9) for the jerk lower limit in
step S88, so as to speed up control of the jerk J within the limits.
Then, the ECU 10 corrects the acceleration A2 and the maximum speed
Vn according to the following equations, so as to satisfy the jerk
limiting condition.

A2=(Vn+1-Vn-1)/(dt1+dt2)+Jmax2×dt2/2×k

Vn=Vn+1+A2×dt2

Namely, when the jerk is smaller than the lower limit, the ECU 10 corrects
the speed of the middle one of the three adjacent points which has the
highest speed, to a lower speed.

[0140]In step S89, the ECU 10 determines whether the operation to correct
the maximum speed Vn is completed over a range from the point
located ahead of the running end point to the second point as counted
from the running start point. If it is determined that the operation to
correct the maximum speed Vn has not been completed with respect to
all of the regions, the ECU 10 sets a region C that is retracted by one
region from the region (point) C that has been processed toward the
running start point, in step S89, and repeats the process of steps
S86-S89. Then, if it is determined in step S88 that the operation to
correct the maximum speed Vn is completed over the range from the
point located ahead of the running end point to the second point as
counted from the running start point, the process of FIGS. 10A and 10B
ends.

[0141]If the operation to correct the maximum speed Vn is performed
on the speed pattern, using jerks between the running end point and the
running start point, the vehicle speed is adequately corrected at points
where the speed increases after decreasing in each of the sections into
which each curved traveling path is divided, as indicated by the thick
line in FIG. 11.

[0142]Thus, in the vehicle running control system 1 of the third
embodiment, the ECU 10 calculates a jerk (i.e., rate of change of
acceleration) across adjacent regions, and compares the jerk with
predetermined limit values (the upper limit and the lower limit), so as
to perform a speed correcting operation.

[0143]Thus, the vehicle running control system 1 of the third embodiment
is able to create a relatively stable speed pattern, without causing a
significant change in the posture of the vehicle against pitching of the
vehicle, thus assuring improved ride comfort.

[0144]When speed changes over adjacent regions C assume a concave or
recessed shape, the vehicle running control system 1 of the third
embodiment corrects a speed condition of the region C having the highest
speed and located at the leading side in the direction of progression of
the correcting operation, to a lower speed. When speed changes over
adjacent regions C assume a convex shape, on the other hand, the control
system 1 corrects a speed condition of the middle region C having the
highest speed, to a lower speed. Thus, speed correction can be optimally
made in accordance with speed changes over adjacent regions.

[0145]FIG. 13 is a flowchart illustrating a process of creating a speed
pattern according to a traveling path, which is executed by a vehicle
running control system 1 according to a fourth embodiment of the
invention. The overall configuration of the vehicle running control
system 1 of this embodiment is substantially the same as that of the
first embodiment as described above, and will be described with reference
to FIG. 1. Also, the same reference numerals as used in the first
embodiment are assigned to members or components having the same or
similar functions as those of the first embodiment, and explanation of
these members or components will not be repeated.

[0146]In the vehicle running control system 1 of the fourth embodiment,
the first speed condition correcting unit and second speed condition
correcting unit compare the jerk with predetermined upper limit and lower
limit (limit values), so as to perform a speed correcting operation. In
this embodiment, in particular, the upper limit and the lower limit are
set in accordance with the shape of the target traveling path.

[0147]More specifically described, the vehicle running control system 1 of
the fourth embodiment has a process to be carried out during the process
of creating a speed pattern in the third embodiment as described above.
Namely, in the process of creating a speed pattern in the third
embodiment, the speed pattern is corrected, using the limit values of the
jerk, so as to prevent instability in the posture of the vehicle due to
pitching of the vehicle. In this case, if the line to be traveled shifts
from a straight line to a curve, such that the turning radius R changes
by a great degree, the speed pattern will be such that steering of the
vehicle is effected after the deceleration returns to zero from full
braking. This speed pattern is the optimum solution as long as the
vehicle is regarded as one mass point. In the actual vehicle, however,
the load of the front wheels for causing the yaw rate to appear in the
vehicle is removed or reduced, and the speed pattern may be inappropriate
for running the vehicle rapidly and safely.

[0148]Therefore, when the line to be traveled shifts from a straight line
to a curve, the vehicle running control system 1 of the fourth embodiment
sets a limit value of the jerk to a smaller value (e.g., 3 m/s3) in
a condition where the acceleration is largely negative (e.g., -0.2 G or
less) and the jerk is positive, namely, in a condition where the vehicle
starts cornering with the braking force being reduced, so as to prevent
the load of the front wheels from being removed or reduced. The fourth
embodiment may be implemented only by changing the limit value of the
jerk during the process of creating a speed pattern in the third
embodiment as described above. Even if the upper limit of the jerk is
lowered (made more rigorous) at a point where the vehicle enters a curve,
the vehicle will not enter the curve while it is simply too decelerated,
but a point at which the vehicle starts being decelerated is adjusted so
that the speed is optimally adjusted within that range. Since the vehicle
that runs from a straight line to a curve requires force derived from the
load of the front wheels for causing the vehicle to start turning in the
yawing direction, which force is increased as changes in the yaw rate
along the curve are larger, the jerk limit value is set to a lower value
as changes in the yaw rate (differential values of the yaw rate) along
the curve are larger.

[0149]A process of creating a speed pattern according to a traveling path,
which is executed by the vehicle running control system 1 of the fourth
embodiment, will be described in detail with reference to the flowchart
of FIG. 13.

[0150]The process of creating a speed pattern according to a traveling
path with the vehicle running control system 1 of the fourth embodiment
is carried out during the speed pattern creating process (the flowchart
of FIG. 10A and FIG. 10B) of the third embodiment. Namely, as shown in
FIG. 13, the ECU 10 sets a region of the running start point in step
S101, and determines in step S102 whether the acceleration of the vehicle
is smaller than -0.2G. If it is determined in step S102 that the vehicle
acceleration is equal to or larger than -0.2 G, the control proceeds to
step S109.

[0151]If, on the other hand, it is determined in step S102 that the
vehicle acceleration is smaller than -0.2 G, the ECU 10 determines in
step S103 whether the jerk is larger than 1 m/s3. While this step is
intended to determine whether the jerk is a positive value, the ECU 10
compares the jerk with 1 m/s3 in view of errors, or the like. If it
is determined in, step S103 that the jerk is equal to or smaller than 1
m/s3, the control proceeds to step S109. If, on the other hand, it
is determined in step S103 that the jerk is larger than 1 m/s3, the
ECU 10 determines in step S104 whether the vehicle is running on a curve,
namely, whether the turning radius R of the vehicle is equal to or
smaller than 300 m. If it is determined that the turning radius R of the
vehicle is larger than 300 m, the control proceeds to step S109.

[0152]If, on the other hand, it is determined that the turning radius R of
the vehicle is equal to or smaller than 300 m, the ECU 10 sets the
upper-limit jerk Jmax1 to a smaller value in step S105. While the
upper-limit jerk Jmax1 is set to 6 m/s3 in the third embodiment
as described above, the upper-limit jerk Jmax1 is set to 3 m/s3
in step S105 in the fourth embodiment. In step S106, the ECU 10
calculates a yaw rate γ1 from the relationship between the
speed of a point in the region that is being processed and the turning
radius R, and calculates a yaw rate γ2 of a point located
adjacent to this point, so as to calculate a differential value of the
yaw rate from the amount of change thereof, according to the following
equation.

Differential value of yaw rate=(γ2-γ1)dt

[0153]In step S107, the ECU 10 determines whether the yaw-rate
differential value is larger than a predetermined set value. If the
differential value is larger than the set value, the ECU 10 sets the
upper-limit jerk Jmax1 to an even lower value, for example, sets the
upper-limit jerk Jmax1 to 2 m/s3.

[0154]In step S109, the ECU 10 determines whether the operation to correct
the upper-limit jerk is completed over a range from the running start
point to the running end point. If it is determined that the correcting
operation has not been completed, the ECU 10 repeats the process of steps
S102-S109 so as to perform the correcting operation on the next region.
Then, if it is determined in step S109 that the operation to correct the
upper-limit jerk is completed over the range from the running start point
to the running end point, the ECU 10 finishes the process of FIG. 13.

[0155]Thus, in the vehicle running control system 1 of the fourth
embodiment, the ECU 10 compares the jerk with the predetermined upper
limit and lower limit so as to perform a speed correcting operation, and
the upper limit and the lower limit are set in accordance with the shape
of the target traveling path.

[0156]Accordingly, the vehicle running control system 1 of the fourth
embodiment creates a speed pattern that ensures a sufficient load of the
front wheels and enables the vehicle to turn with appropriate yawing when
the vehicle enters a curved path, thus assuring increased safety and
improved ride comfort.

[0157]FIG. 14 is a flowchart illustrating a process of creating a speed
pattern according to a traveling path, which is executed by a vehicle
running control system 1 according to a fifth embodiment of the
invention. The overall configuration of the vehicle running control
system 1 of this embodiment is substantially the same as that of the
first embodiment as described above, and will be described with reference
to FIG. 1. Also, the same reference numerals as used in the first
embodiment are assigned to members or components having the same or
similar functions as those of the first embodiment, and explanation of
these members or components will not be repeated.

[0158]In the vehicle running control system 1 of the fifth embodiment,
while the first speed condition correcting unit and second speed
condition correcting unit correct speed conditions while regarding the
vehicle as a mass-point model, the correcting units also correct lateral
force conditions while regarding the vehicle as a rigid body model, after
the operation to correct a speed condition for each of the regions into
which the traveling path is divided is completed.

[0159]Described more specifically, the vehicle running control system 1 of
the fifth embodiment has a process to be carried out during the process
of creating a speed pattern according to the first embodiment as
described above. Namely, in the process of creating a speed pattern in
the first embodiment, the vehicle is regarded as one mass point.
Therefore, in a situation where the yaw rate changes frequency, such as
during slalom running of the vehicle, lateral force for causing the
vehicle to turn in the yawing direction while overcoming the yaw rate of
the vehicle cannot be generated, and the tires may slip. In the third and
fourth embodiments as described above, an effect of stabilizing the
posture of the vehicle is provided by correcting the speed using the
jerk. However, it is essentially and physically difficult to force the
vehicle that enters a curve while running at an extremely high speed to
turn about itself, thus, the speed of the vehicle needs to be
appropriately reduced.

[0160]Therefore, the vehicle running control system 1 of the fifth
embodiment reduces the speed while not only regarding the vehicle as one
mass point, but also treating the vehicle as a rigid body having the
moment of inertia at the yaw rate. Namely, when the vehicle enters a
curved path from a straight path and turns, the load on the front wheels
increases so as to increase the yaw rate. The vehicle running control
system 1 reduces the speed so that the tires lie within the friction
circles even if the increased load is applied to the front wheels. More
specifically, when the absolute value of the yaw rate increases, and the
degree (or rate) of change of the yaw rate (differential value of the yaw
rate) is larger than a set value, the lateral force which causes the
vehicle to turn only by means of the front wheels is added to the lateral
force required by the vehicle as a whole (the moment of inertia at the
yaw rate×differential value of the yaw rate/distance from the
position of the gravity of the vehicle to the front axle), so as to
reduce the speed of the vehicle. If, on the other hand, the absolute
value of the yaw rate decreases, and the degree of change of the yaw rate
(differential value of the yaw rate) is larger than a set value, the
lateral force applied to the front wheels may be reduced to be lower than
that applied to the front wheels; therefore, the above-described
operation is not performed.

[0161]A process of creating a speed pattern according to a traveling path,
which is executed by the vehicle running control system 1 of the fifth
embodiment, will be described in detail with reference to the flowchart
of FIG. 14.

[0162]The vehicle running control system 1 of the fifth embodiment carries
out the process of creating a speed pattern according to a traveling
path, during execution of the speed pattern creating process of the first
embodiment (as illustrated in the flowchart of FIG. 2). Namely, as shown
in FIG. 14, the ECU 10 sets a region of the running start point in step
S111, calculates a yaw rate γ1 from the relationship between
the speed of a point in the region that is being processed and the
turning radius R, and calculates a yaw rate γ2 of a point
located adjacent to the above point, in step S112. Then, the ECU 10
determines in step S113 whether the absolute value of the yaw rate
γ1 is smaller than the absolute value of the yaw rate
γ2.

[0163]If it is determined that the absolute value of the yaw rate
γ1 is equal to or larger than the absolute value of the yaw
rate γ2, the control proceeds to step S117. If, on the other
hand, it is determined that the absolute value of the yaw rate
γ1 is smaller than the absolute value of the yaw rate
γ2, the ECU 10 calculates a differential value of the yaw rate
from the amount of change of the yaw rate in step S114, according to the
following equation.

Differential value of yaw rate=(γ2-γ1)dt

[0164]Then, the ECU 10 determines in step S115 whether the differential
value of the yaw rate is larger than a predetermined set value (e.g., 0
deg/s2). If it is determined that the differential value of the yaw
rate is equal to or smaller than the set value, the control proceeds to
step S117. If, on the other hand, it is determined that the differentia
value of the yaw rate is larger than the set value, the ECU 10 calculates
a lateral force Ay2 required to provide the differential value of
the yaw rate of the vehicle in step S116, according to the following
equation.

Ay2=I×γ/Lf

where, I is the moment of inertia at the yaw rate, and Lf is the distance
from the position of the gravity of the vehicle to the front axle.

[0165]Also, the ECU 10 calculates a lateral force Ay1 using the
coefficient of friction μ of the road and the gravitational
acceleration g, according to the following equation.

Ay1=μ×g

Then, the coefficient of friction μ of the road is changed into a
deemed coefficient of friction μ in view of the moment of inertia at
the yaw rate, according to the following equation.

Deemed coefficient of friction
μ=μ×Ay1/(Ay1+Ay2)

[0166]In step S117, the ECU 10 determines whether the operation to correct
the coefficient of friction μ is completed over a range from the
running start point to the running end point. If it is determined that
the correcting operation has not been completed, the ECU 10 repeats the
process of steps S112-S117 so as to perform a correcting operation on the
next region C. Then, if it is determined in step S117 that the operation
to correct the coefficient of friction μ is completed over the range
from the running start point to the running end point, the ECU 10
finishes the process of FIG. 14.

[0167]Thus, in the vehicle running control system 1 of the fifth
embodiment, when the ECU 10 performs an operation to correct a speed
condition for each of the regions into which the target traveling path is
divided, the ECU 10 corrects lateral force conditions while regarding the
vehicle as a rigid-body model, after completing the operation to correct
speed conditions while regarding the vehicle as a mass-point model.

[0168]It is thus possible to create an appropriate speed pattern according
to which the vehicle runs while turning about itself in a running
condition, such as slalom running, in which the yaw rate changes
frequently.

[0169]In the illustrated embodiments, the vehicle running control system 1
according to the invention is applied to automatic running control of the
vehicle. However, the vehicle running control system of the invention may
be applied to vehicles capable of automatic running control and manual
running control.

[0170]Next, a vehicle running control system 1 according to a sixth
embodiment of the invention will be described in detail. Initially, the
arrangement of ECU (electronic control unit) 10 and other components of
the vehicle running control system 1 will be described with reference to
FIG. 15.

[0172]The speed pattern creating unit 1a creates a speed pattern (or an
acceleration pattern), based on information on the shape of a traveling
course (for example, information on the turning radius R of the road,
information on the coefficient of friction μ between the tires and the
road surface), and driver-requested tasks (for example, the destination
or location of a goal, arrival time, and the importance placed on the
fuel efficiency). The speed pattern thus created is concerned with
changes in the speed (or acceleration) which lead to a result evaluated
as the optimum while fulfilling the requested tasks. More specifically,
when the location of the goal and the time at which the vehicle is
expected to reach the goal are set as requested tasks, the speed pattern
creating unit 1a creates a speed pattern that is evaluated as providing
the highest fuel efficiency within a range in which the set conditions
are satisfied. FIG. 16 shows one example of speed pattern created by the
speed pattern creating unit 1a.

[0173]Referring back to FIG. 15, the traveling path dividing unit 1b
divides the speed pattern obtained in the speed pattern creating unit 1a
into a plurality of regions C depending on the running conditions. In
other words, the traveling path dividing unit 1b divides a given
traveling course into a plurality of regions C, in accordance with the
target speed or target acceleration. In order to improve the fuel
efficiency as much as possible, "acceleration" and "coasting" using no
engine brake are incorporated as running conditions (running patterns).
In this embodiment in which great importance is placed on the fuel
efficiency, the speed pattern is divided into two regions, i.e.,
"acceleration region" as a region C in which the speed is increased, and
"coasting region" as a region C in which the vehicle coasts substantially
with the rolling resistance alone. FIG. 17 shows one example of
acceleration region and coasting region into which the traveling course
is divided by the traveling path dividing unit 1b, along with the
traveling course.

[0174]Referring back to FIG. 15, the assist control unit 1c performs
assist control that places importance on the fuel efficiency, based on
the speed pattern created by the speed pattern creating unit 1a and the
regions defined by the traveling path dividing unit 1b. More
specifically, in the acceleration region, the assist control unit 1c
performs assist control of one or both of "needless acceleration
limitation (restriction)" and "acceleration assist", according to a
deviation between the target acceleration and the driver-requested
acceleration. In the coasting region, the assist control unit 1c performs
assist control of one of "acceleration limitation (restriction)" and
"coasting assist", depending on the ON/OFF state of the accelerator
pedal. FIG. 18 shows one example of the relationship between the region
and the assist control.

[0175]The "needless acceleration limitation (restriction)" is assist
control for placing limitation or restriction on the requested
acceleration entered by the driver, when the driver-requested
acceleration exceeds the target acceleration pattern. The "acceleration
assist" is assist control for increasing the acceleration to be larger
than the requested acceleration entered by the driver within a range in
which the increased acceleration does not pose a danger nor causes the
driver to feel uncomfortable, when the driver-requested acceleration
falls below the acceleration pattern, which makes it difficult to achieve
the task(s) set by the driver.

[0176]In this connection, a coordination method taking account of the
driver's feeling (such as discomfort), according to which both of the
assist controls, "needless acceleration limitation" and "acceleration
assist", can be implemented at the same time, will be explained. The
acceleration requested by the driver and a target value of acceleration
set by a driving force control system are coordinated, based on the
Weber-Fechner's law (E[dB]=K×log(R)) that "the amount of perception
E is proportional to the logarithm of stimulus R", and a command value of
acceleration is set. For the amount of perception E, there is a
differential threshold as an amount of change dE [dB] of stimulus, based
on which it is determined whether a change of stimulus relative to the
current stimulus (acceleration) is noticeable or not. The differential
threshold is set for each of the increase side and decrease side of the
absolute value of the acceleration, with reference to the
driver-requested acceleration. In the driving force control of the
vehicle, the acceleration applied to the driver is the same
(substantially the same) as the acceleration of the vehicle, and the
acceleration applied to the driver changes similarly to the acceleration
of the vehicle when it is changed. In other words, the amount of
perception E of the driver may be calculated using the acceleration of
the vehicle as stimulus R, instead of the acceleration applied to the
driver.

[0177]Also, a threshold dE/dt [dB/s] is provided based on which it is
determined whether a change of stimulus with time is noticeable. The
time-series differential threshold has two values of the increase side of
the absolute value (the upper limit of the amount of correction of jerk
as will be described later) and the decrease side (the lower limit of the
jerk correction amount), with reference to the driver-requested jerk.
Guard values are respectively set for the acceleration (driving force)
and the rate of change of acceleration, based on the differential
thresholds based on which it is determined whether a change of the
acceleration is noticeable, and the time-series differential thresholds
based on which it is determined whether a change of the jerk is
noticeable. Furthermore, when the amount of operation of the accelerator
pedal or brake pedal by the driver changes largely in a short time,
namely, when the driver desires a large change in the acceleration, the
guard value set for the rate of change of acceleration is relaxed.

[0178]Returning to the explanation of the assist control unit 1c, the
"acceleration limitation (restriction)" is assist control for positively
limiting or reducing the driver-requested acceleration in the coasting
region when the driver places the accelerator pedal in the ON state. The
assist control of the acceleration limitation is set in this manner,
because it can be determined that there is basically no need to
accelerate the vehicle in the coasting region (in other words, the set
task(s) can be satisfactorily accomplished without accelerating the
vehicle). The "coasting assist" is assist control for coasting the
vehicle (with no torque produced by the vehicle) without applying engine
brake to the vehicle when the driver places the accelerator pedal in the
OFF state.

[0179]This embodiment has features (advantages) that (1) the control side
has a target speed/acceleration pattern, and (2) the control side knows
what running condition (running pattern) the vehicle should be in, at a
certain position (region) on the course, (for example, what is needless
in the acceleration region). With this arrangement, the control side is
able to perform positive and effective assist control, in response to the
operational input of the driver.

[0180]Referring back to FIG. 15, the region display unit 1d displays the
status (more specifically, "acceleration" or "coasting") of the running
condition (running pattern) at the position (region) where the vehicle is
currently running, on a region indicator 8 installed on the vehicle. One
example of the region indicator 8 will be described with reference to
FIG. 19A and FIG. 19B. The region indicator 8 consists of a pair of
indicators MA1 and MA2 as shown in FIG. 19A. The indicator MA1 clearly
indicates that the current region is an acceleration region, and presents
a content requested to the driver, by means of, for example, letters and
lighting, and the indicator MA2 clearly indicates that the current region
is a coasting region, and presents a content requested to the driver, by
means of, for example, letters and lighting. As shown in FIG. 19B, the
region display unit 1d switches lighting of the indicators MA1 and MA2,
based on the region information at the current position. In the examples
of FIG. 19A and FIG. 19B, "Accel Accel On" is one example of letters
corresponding to clear indication of the acceleration region and
presentation of the request for accelerator pedal ON, and "FreeRun) Accel
Off" is one example of letters corresponding to clear indication of the
coasting region and presentation of the request for accelerator pedal
OFF.

[0181]Referring back to FIG. 15, the setting unit 1e sets an evaluation
point in steps, with respect to a deviation between a controlled variable
associated with the target speed in the speed pattern and a controlled
variable associated with the speed entered by the driver (for example, a
difference between the target speed and the driver input speed), or a
deviation between a controlled variable associated with the target
acceleration in the acceleration pattern and a controlled variable
associated with the acceleration entered by the driver (for example, a
difference between the target acceleration and the driver input
acceleration).

[0182]The evaluation display unit 1f displays the evaluation point set by
the setting unit 1e, on an evaluation indicator 9 installed on the
vehicle. One example of the evaluation indicator 9 will be described with
reference to FIG. 20A and FIG. 20B. The evaluation indicator 9 is an
indicator MB as shown in FIG. 20A. The indicator MB consists of a
plurality of (preferably, an odd number of) sections that correspond to
the respective evaluation points and can be illuminated, and is operable
to indicate the evaluation point set by the setting unit 1e by lighting
up an appropriate one of the sections. The evaluation display unit 1f
defines (determines) the section corresponding to the evaluation point,
and lights up the section thus determined, as indicated in FIG. 20B.

[0183]In this embodiment, the control side positively and effectively
performs assist control in response to the operational input of the
driver. In addition, the control side positively gives information
possessed by or known to the control side to the driver via the
indicator(s). Owing to these interactions between the driver and the
control side, the compatibility between the operation of the driver and
vehicle control can be further improved, and further enhanced performance
for improved fuel efficiency can be achieved.

[0184]Next, one example of main operation performed by the ECU 10
configured as described above will be described with reference to FIG.
21. FIG. 21 is a flowchart illustrating one example of main operation of
this embodiment.

[0185]Initially, the ECU 10 obtains road shape information and the
coefficient of friction μ between the tires and the road surface, as
information to be read in advance (step SA1).

[0186]Then, the speed pattern creating unit 1a of the ECU 10 creates a
target speed/acceleration pattern (including a speed pattern) according
to which driver-requested tasks, including the target arrival time and
the optimum fuel efficiency, are accomplished, based on the information
obtained in step SA1 (step SA2).

[0187]As one example of method of calculating the speed pattern, the road
is divided into acceleration regions and coasting regions (deceleration
regions), and the speed pattern is calculated using different evaluation
functions for the acceleration regions and coasting regions,
respectively. More specifically, running conditions (running pattern) of
the vehicle when running on a road are predicted, based on road shape
information stored in a road shape information file, and the road is
divided into two or more road regions, based on the predicted running
conditions (running pattern). Then, an evaluation function for each road
region is set, and the traveling track of the vehicle running on the road
is calculated, based on the evaluation functions set for the respective
road regions. Also, the ECU 10 calculates the traveling track, using the
positions at which the road is divided into the road regions as variable
conditions. The traveling track indicates the position of the vehicle
running on a traveling course (target traveling path).

[0188]The ECU 10 calculates a predicted speed pattern the vehicle is
expected to follow when running on the road, based on road shape
information stored in the road shape information file, divides the road
into at least an acceleration region and a deceleration region as road
regions, based on the calculated speed pattern, and sets an evaluation
function for acceleration region at the acceleration region and an
evaluation function for deceleration region at the deceleration region.
For the acceleration region, an evaluation function that evaluates the
case where the engine speed is equal to or higher than a middle speed as
being more desirable than the case where the engine speed is around zero,
is set. More specifically, the ratio of the thermal efficiency of each
point (region) when the best point of the thermal efficiency of the
engine is equal to 1 is obtained, and an evaluation function that gives
an evaluation value by subtracting 1 from the total value of the entire
system is set, such that the evaluation value when the engine speed is
around zero is a numerical value larger than 0. For the deceleration
region, an evaluation function that evaluates the case where engine speed
is around zero as being mode desirable than the case where the engine
speed is equal to or higher than a middle speed is set. More
specifically, an evaluation function is set which provides an evaluation
value equal to a numerical value that is proportional to the loss of
energy input/output in a hybrid system, with respect to the
acceleration/deceleration energy released from the deceleration of the
rolling resistance, when the rolling resistance is set at 0 as a
reference, and the evaluation value when the engine speed is equal to or
higher than a middle speed is a numerical value larger than 0.

[0189]Also, the ECU 10 calculates a predicted rate of usage of friction
circle when the vehicle runs on the road, based on road shape information
stored in the road shape information file, and sets different evaluation
functions with respect to a road region where the calculated rate of
usage of friction circle is relatively high, and a road region where the
calculate rate of usage of friction circle is relatively low. More
specifically, the ECU 10 sets an evaluation function for the acceleration
region, which evaluates it as being desirable to accelerate the vehicle
with the engine basically in a rotating state while utilizing a hybrid
system for improvement in the fuel efficiency, and sets an evaluation
function for the deceleration region, which evaluates it as being
desirable to decelerate the vehicle with the engine basically in the OFF
state while utilizing regenerative braking and electric power assist.

[0190]Next, another example of calculation of the speed pattern will be
described. The ECU 10 corrects a normally created speed pattern
(steady-state circle maximum speed pattern) by correcting speed
conditions in a direction from the start position of running control
toward the end position thereof, and correcting speed conditions in a
direction from the end position of running control toward the start
position thereof, so as to calculate a speed pattern. More specifically,
the ECU 10 is configured to create a speed pattern along a target
traveling path (course), and control running of the vehicle based on the
speed pattern, and includes a first speed condition correcting unit that
performs an operation to correct speed conditions in a direction from the
start position of running control to the end position of running control
on the target traveling path, and a second speed condition correcting
unit that performs an operation to correct speed conditions in a
direction from the end position of running control to the start position
of running control on the target traveling path. Thus, the ECU 10
corrects the speed conditions in the direction from the start position to
end position of running control on the target traveling path, and
corrects the speed conditions in the direction from the end position to
start position of running control, without using the optimization method,
so as to create a speed pattern according to the traveling path within a
short time. Also, the ECU 10 corrects acceleration-side speed conditions
that provide accelerations in the speed pattern, and also corrects
deceleration-side speed conditions that provide decelerations in the
speed pattern. In this case, the ECU 10 corrects appropriate ones of the
speed conditions to lower speeds.

[0191]Also, the ECU 10 includes a traveling path dividing unit that
divides the target traveling path into a plurality of regions at fixed or
given intervals, and performs a correcting operation on a speed condition
for each of the regions C into which the traveling path is divided.
Specifically, the ECU 10 compares speed conditions of adjacent regions C,
and corrects the speed condition of the higher-speed region C to a lower
speed. In this case, an acceleration or a deceleration is determined by
comparing the speeds of adjacent regions C, and a correcting operation is
performed so that the acceleration or deceleration does not exceed the
upper limit. Thus, the ECU 10 divides the target traveling path into a
plurality of regions C at fixed intervals, and performs a correcting
operation on each of the regions C to correct appropriate ones of the
speed conditions to lower speeds.

[0192]The ECU 10 may calculate a deceleration across adjacent points set
in sequence in a direction from the running end point toward the running
start point, after calculating an acceleration across adjacent points set
in sequence in a direction from the running start point toward the
running end point, with respect to the steady-state circle maximum speed
pattern of the target traveling path. Also, the ECU 10 may calculate an
acceleration across adjacent points set in sequence in the direction from
the running start point toward the running end point, after calculating a
deceleration across adjacent points set in sequence in the direction from
the running end point toward the running start point, with respect to the
steady-state circle maximum speed pattern of the target traveling path.

[0193]Referring back to FIG. 21, the traveling path dividing unit 1b of
the ECU 10 divides the target speed/acceleration pattern created in step
SA2 into two regions, i.e., "acceleration region" and "coasting region",
based on the running conditions in the target speed/acceleration pattern
(step SA3).

[0194]Then, the assist control unit 1c of the ECU 10 performs assist
control according to the regions C defined by the traveling path dividing
unit 1b in step SA3 while monitoring the actual running of the vehicle
(step SA4).

[0195]More specifically, when the actual running position of the vehicle
is in the acceleration region C defined by the traveling path dividing
unit in step SA3 (YES in step SA41), the assist control unit 1c of the
ECU 10 performs assist control of "acceleration assist" as described
above (step SA43) when the driver input acceleration estimated from the
current amount of depression of the accelerator pedal, amount of
depression of the brake pedal and the vehicle speed falls below the
target acceleration (YES in step SA42). If, on the other hand, the driver
input acceleration is equal to or larger than the target acceleration (NO
in step S42), the ECU 10 performs assist control of "needless
acceleration limitation" as described above (step SA44). More
specifically, the ECU increases a gain of a map of the relationship
between the accelerator pedal depression and the requested acceleration,
as assist control of "acceleration assist", in step SA43, and reduces the
gain of the map of the accelerator pedal depression and the requested
acceleration, as assist control of "needless acceleration limitation", in
step SA44.

[0196]Also, when the actual running condition of the vehicle is not in the
acceleration region C defined by the traveling path dividing unit in step
SA3 (NO in step SA41), but the actual running condition is in the
coasting region (YES in step SA45), the assist control unit 1c of the ECU
10 performs assist control of the above-described "acceleration
limitation" (step SA47) if the driver places the accelerator pedal in the
ON state (YES in step SA46), and performs assist control of the
above-described "coasting assist" (step SA48) if the driver places the
accelerator pedal in the OFF state (NO in step SA46). More specifically,
the ECU 10 largely reduces the gain of the map of the relationship
between the accelerator pedal depression and the requested acceleration,
as assist control of "acceleration limitation", in step S47. In this
connection, the reduced gain used in the "acceleration limitation"
performed in step SA47 may be set to be larger than the reduced gain used
in the "needless acceleration limitation" performed in step SA44. In step
SA48, the ECU 10 performs assist control of "coasting assist", by making
torque generated by the vehicle equal to zero when the vehicle is an HV
(hybrid) vehicle, or causing the vehicle to run as if the N (neutral)
range is selected when the vehicle is a MT (manual transmission) vehicle.

[0197]When the actual running position of the vehicle is not in the
coasting region (NO in step SA45), the assist control unit 1c of the ECU
10 does not perform assist control (step SA49). For example, if the gain
of the map is changed, the gain is returned to the original state.

[0198]Returning to the explanation of the main operation of FIG. 21, the
ECU 10 controls the output of each actuator (step SA5) so as to carry out
the assist control selected in step SA4. More specifically, the ECU 10
controls the output of the throttle actuator 6, etc., so that the vehicle
runs according to the map of the accelerator pedal depression and the
requested acceleration, for which the gain is changed as needed through
execution of the assist control in step SA4.

[0199]Next, one example of region display operation performed by the ECU
10 configured as described above will be described with reference to FIG.
22. FIG. 22 is a flowchart illustrating one example of the region display
operation of this embodiment.

[0200]Initially, when the actual running condition of the vehicle is in
the acceleration region (YES in step SB1), the region display unit 1d of
the ECU 10 turns on the indicator MA1 and turns off the indicator MA2
(step SB2).

[0201]Also, when the actual running condition of the vehicle is not in the
acceleration region (NO in step SB1), the region display unit 1d of the
ECU 10 turns off the indicator MA1 and turns on the indicator MA2 (step
SB4) if it is in the coasting region (YES in step SB3), and turns off
both the indicator MA1 and the indicator MA2 (step SB5) if it is not in
the coasting region (NO in step SB3).

[0202]Next, one example of evaluation point display operation performed by
the ECU 10 configured as described above will be described with reference
to FIG. 23. FIG. 23 is a flowchart illustrating one example of evaluation
point display operation of this embodiment.

[0203]Initially, the setting unit 1e of the ECU 10 obtains a difference
"input acceleration-target acceleration" between the driver's input
acceleration estimated from the current accelerator pedal input amount,
brake pedal input amount and the vehicle speed, and the target
acceleration, as a deviation (step SC1).

[0204]Then, the setting unit 1e of the ECU 10 sets an evaluation point
stepwise, for the deviation obtained in step SC1, based on a
predetermined map defining the relationship between the deviation and the
evaluation point (step SC2).

[0205]Then, the evaluation display unit 1f of the ECU 10 defines
(determines) a section corresponding to the evaluation point set in step
SC2, from among a plurality of sections that constitute the indicator MB,
and turns on the determined section (step SC3). More specifically, the
illuminated section indicating the evaluation point is located further to
the right relative to the middle of the indicator MB as the evaluation
point increases, so that the ECU 10 can inform the driver that the amount
of depression of the accelerator pedal by the driver is too large, as
shown in FIG. 20A and FIG. 20B. Also, the illuminated section indicating
the evaluation point is located further to the left relative to the
middle of the indicator MB as the evaluation point decreases, so that the
ECU 10 can inform the driver that the amount of depression of the
accelerator pedal by the driver is too small, as shown in FIG. 20A and
FIG. 20B. Also, the middle section of the indicator MB is illuminated
when the evaluation point is intermediate, so that the ECU 10 can inform
the driver that the driver depresses the accelerator pedal by an
appropriate degree, as shown in FIG. 20A and FIG. 20B.

[0206]As explained above, the vehicle running control system of this
embodiment creates a target speed pattern (target speed controlled
variable pattern) using the shape of the course and other information,
divides the created target speed pattern into a plurality of
speed-pattern regions, and performs assist control on the driver's
operation depending on the regions into which the speed pattern is
divided. Thus, the system is able to perform the optimum assist control
according to the target speed pattern, to meet with the driver's
request(s), and efficiently perform control for coordination between the
traveling plan and the driver's operation, so that the actual running
result of the vehicle becomes closer to the traveling plan.

[0207]According to this embodiment, the information concerning regions,
such as "acceleration region" and "coasting region", information
concerning requests for operations by the driver, such as "accelerator
pedal ON" and "accelerator pedal OFF", and information concerning the
deviation between the target pattern and the driver's input are displayed
on the indicators. Thus, even when assist control is positively effected
on the vehicle side, the driver is prevented from feeling uncomfortable
about the assist control or feeling that the assist control is abruptly
executed. Also, according to this embodiment, the control side has a
target speed/acceleration pattern, and is aware of what running condition
(running pattern) the vehicle should be in at a certain location
(region); therefore, the control side performs positive running control
and positively gives the driver the above-indicated items of information,
thus assuring further improved compatibility between the driver's
operation and vehicle control, due to the interactions between the
control side and the vehicle side. Consequently, the above-mentioned
tasks can be accomplished with further enhanced performance,

[0208]The system of the invention creates a pattern of a controlled
variable associated with the speed to be achieved during running of the
vehicle, as a speed pattern, divides the created speed pattern into a
plurality of regions depending on the running conditions, and performs
assist control for assisting in achievement of the traveling plan, for
each of the regions, so that vehicle control based on the traveling plan
and the driver's operation can be coordinated with further efficiency,
thus providing an effect that the traveling plan can be accomplished with
further reliability.

[0209]The system of the invention outputs information concerning the
running conditions corresponding to the regions, and/or information about
the deviation between the controlled variable concerning the speed in the
speed pattern and the controlled variable concerning the speed entered by
the driver to the vehicle, such that the output information can be
visually and/or audibly recognized, thus assuring improved compatibility
between the vehicle control based on the traveling plan and the driver's
operation. As a result, the traveling plan can be accomplished with
further improved reliability. In other words, the vehicle running control
system of this embodiment performs positive assist control, and
positively gives information concerning running conditions and
information concerning the deviation, to the driver, thus assuring
improved compatibility between the driver's operation and the vehicle
control due to the interaction therebetween. Consequently, the traveling
plan can be accomplished with further enhanced performance. Also, the
vehicle running control system of this embodiment outputs information
concerning the running conditions, and/or information concerning the
deviation between the speed pattern and the driver's input; therefore,
even when assist control is positively effected on the vehicle side, the
driver is prevented from feeling uncomfortable with the assist control or
feeling that the assist control is abruptly executed.

[0210]In this embodiment, the control side creates a traveling plan
including a target speed pattern or target acceleration pattern (target
speed controlled variable pattern as a pattern of a controlled variable
associated with the speed) according to a given course (target traveling
path) and tasks (including, for example, the destination, target arrival
time to the destination, and importance placed on the fuel efficiency),
divides the created target speed pattern or target acceleration pattern
into regions in accordance with the running conditions (running pattern),
and positively switches assist control, depending on the regions, for
improvement of the fuel efficiency, thus making it possible to
significantly improve the fuel efficiency as compared with general
systems.

[0211]In this embodiment, HMI (human machine interface) elements are
classified into "indication", "suggestion" and "evaluation", and the HMI
corresponding to these items of classification are installed, so as to
prevent the driver from feeling uncomfortable when the system positively
performs assist control on the vehicle side or when the assist control is
switched from one mode to another or feeling that the assist control or
switching thereof is abruptly executed. In addition, the system asks the
driver to cooperate with the system to accomplish the tasks, thus making
it possible to achieve further improved performance for improvement of
the fuel efficiency.

[0212]The element of "indication" enables the driver to be aware of "what
the control side is currently doing" and "what kind of assist is going to
be provided". The element of "suggestion" enables the driver to be aware
of "what the control side wants the driver to do". The element of
"evaluation" enables the driver to be aware of "how much the driver's
operations and inputs contribute to accomplishment of the tasks".

[0213]While the invention has been described with reference to example
embodiments thereof, it is to be understood that the invention is not
limited to the described embodiments or constructions. To the contrary,
the invention is intended to cover various modifications and equivalent
arrangements. In addition, while the various elements of the example
embodiments are shown in various combinations and configurations, other
combinations and configurations, including more, less or only a single
element, are also within the scope of the invention.